Today’s Backpack Design and Utility

Originally posted at:  https://thetrek.co/appalachian-trail/todays-backpack-design-and-utility/

I started backpacking when I was 16 years old.  My first backpack was an external frame Jansport pack and until just recently I have used the same basic pack on every trip I have taken.  My latest is a Jansport Carson (62 ounces plus a 6 ounce rain cover).  The design is basically the same as my very first pack.  Recently, I have sought out a lighter pack and through my search I have discovered that the basic design of today’s packs has not evolved.  In fact, in many ways I think it has gone backwards.  That being said I will carry a Zpacks Arc Haul Zip (27.5 ounces according to Zpacks) on my AT thru, even though it has a couple of limitations.  I still prefer the basic Jansport or Kelty design for one main reason – organization.

Organization – External vs Internal Frame (or Frame-less) Pack

The basic design of the old external frame packs made packing your pack, and more importantly, finding your gear simple.  Strapped to the top was your tent and strapped to the bottom was your sleeping bag.  The two big side pockets had individual purposes; one for first aid, toiletries, flash light or headlamp and the other for kitchen gear, knife, cord, and other miscellaneous items.  There were two open mesh bottom pockets for water bottles.  The main compartment was accessed with a zipper and it had a shelf (piece of material) in the middle to break it into two compartments.  On the bottom, camp shoes, clothing, pillow, sleepwear.  In the upper, fuel, stove, food and any other miscellaneous camp gear or crew gear if out with a group.  With the zipper I could access any part of the internal compartment without having to disturb the gear around what I was after.

Today’s packs are almost always top loading.  This eliminates the zipper, which I think most consider an advantage.  The zipper adds weight, is something that can break, and water can potentially seep into the pack through the zipper.  Further, since most are top loading the internal shelf had to be eliminated, again a weight saving feature, but it creates one giant black hole.  A lot (most) of the packs have also eliminated outer pockets, with the exception of the two lower pouches for water bottles.  I am unsure as to the reason for this, but I find it to be unfortunate from an organization standpoint.

A view of these differences from the trail….

A couple of years ago I spent a week at Philmont Scout Ranch with a group of adults and youth.  For most of them it was their first longer term backpacking trip (10 days).  One of my best friends could never really figure out his pack.  He never quite knew where his gear was.  Another adult leader had to constantly explode her pack in order to find anything.  Her trail name was Sister Gadget, but that is another story.  The youth all had difficulty knowing where anything was.  Something as quick as grabbing a rain jacket would become a 20 minute pack off break as each of them in turn decided they needed to remove their pack for whatever reason.

Today’s packs remind me of the dry bags we use on Boundary Water canoe trips—one big black hole, everything goes in and you pretty much have to completely empty it to find what you want.  By comparison, my old Jansport external frame made finding any item simple and easy.  My best friend was amazed that could pack my pack in moments and I knew exactly where everything was.  The design of the external frame pack made it easy.

The Focus on Weight

I believe one of the main reasons for the internal frame pack was the focus on weight.  The weight of the external frame put these packs upwards of five pounds.  The internal frame presents some advantages and some issues.  A internal frame or frame-less pack is the only way to carry your gear if you go ultralight.  It is more comfortable as the pack rests close to your body and does not disturb your center of gravity.  The lack of the frame in today’s packs does not matter a great deal with ultralight or very light loads.  The weight can be carried comfortably between your shoulders and hips.  This will allow you to move like a gazelle down the trail.

However, if you are low to mid 20 pounds base weight, then the weight starts to become uncomfortable once loaded with food and water, causing shoulder and neck pain in a lot of cases.  The three main purposes of the external frame were to:  1)support the pack, 2)keep the pack off of your back to provide air flow and 3)to put the weight of the pack on the hip belt and ultimately on your hips, instead of your shoulders.  Further, most internal frames rest tight up against your back.  This makes them feel better from a weight distribution standpoint as they move with you.  Scrambling up a rock face is a lot nicer with an internal frame pack held tight against your body.  The downside to this is that they are hot.  For someone that sweats lot that is a huge issue.  I need the airflow.

The focus on weight has done a disservice to pack design.  I believe you could still have a fairly lightweight pack and maintain most of the convenience and functionality, or utility, of the older design.  Today, it is difficult to find an external frame pack for a long distance hiking (external frame pack with a focus on lightweight materials).

Zpacks Arc Haul Zip Design

My search led me to settle in on the Zpacks Arc Haul Zip.  The main reason I chose this pack is that it has a zipper so I easily access any part of the interior compartment.  Utility and organization.  However, I do miss the sewed on, sealed upper pockets and the interior shelf.  I have solved the external pockets by using stuff sacks equal to the size of the add-on upper pockets.  I have not solved the interior shelf as I don’t have the time to invest in attempting a modification to the pack by adding a compartment divider.  The added weight to the pack would be negligible, if the manufacturer had solved both design issues.

The frame is not as sturdy as the old external frames, but that gives a very nice weight savings.  However, the frame is sufficient for two purposes:  1)it keeps the pack’s weight on my hips and 2)the arc in the frame keeps the pack off my back creating airflow.  The design of the frame does not support the pack as much as the old external frames, but with the significant weight savings, I think it will work for me.

All told I think that Zpacks Arc Haul Zip design is almost perfect.  Sure, I would tweak a couple of things and unfortunately when I asked about modifications, they were unable to do so.  I am looking forward to giving this pack a more complete test on the trail and hope that it meets all my expectations.

The other day I ran into a review of this pack by the co-designer of the pack.  For those you interested in a more detailed explanation of the design of the pack, it is an interesting read.

ZPacks “Arc Zip” Backpack

What are your pack thoughts?

-Scott

Backpack

So, I think I am nuts.  I had my big three all picked out, wrote an article about it even.  But, yesterday I ordered a new backpack.  It comes with a 30 day trial period, so I will put it through its paces and see how I like it.  This was critical as it is a very different design approach to a backpack.  The background on this decision is that my current pack, a Jansport Carson, is beginning to show signs of wear.  It has been used on numerous weekend scout outings, four trips to Philmont, two trips to Isle Royale and tons of preparation hikes.  After a close inspection a while back I determined I that I don’t think it will make the 2,200 miles without breaking down on me.  So I decided to send my two other external frame packs from days gone by back to Jansport for repair or replacement.  My thought was that the repaired packs would be my backup in case of catastrophic failure.  Well, a couple days ago I got my replacement packs.  Two brand new internal frame Jansport packs.  I know I should not be disappointed, but I was.  They won’t work for me.  So the search for a new pack began in earnest.  I immediately thought Kelty, because back in the day you were either Jansport or Kelty.  Now that Jansport is out of the external frame market, I figured I would check into the dark side.  From there, I went literally all over the world looking at packs and I settled in on one made from a cottage industry supplier in Texas.

Here is the website:

http://www.neotrekk.com/index.html

What I like about it is that it is an external frame.  I don’t care what anyone says, but a good external frame supports the weight better than an internal frame.  The only time an internal frame makes good sense to me is when you are going ultralight with a base weight (everything except food and water) under 20 pounds (preferably under 15 pounds), because then you would rarely be carrying weights of 25-30 pounds.  With minimal weight any two shoulder straps and weight belt would do, so the internal frame packs work well in that environment.  Although I care about weight I am not an ultralight packer.

I like the three barrels.  This compartmentalizes my gear, which is what I have with my Jansport Carson backpack through two main compartments, two large side pockets, and tent and sleeping bag attached at the top and bottom.  I like that there are no zippers and that the barrels are waterproof (huge plus).  I like that the hip belt stays on throughout the day and you simply pop the pack off and on.  This could help with the lower back pain that sometimes develops after a practice hike.  The belt may act like those that weight lifters wear and support the lower back better than the traditional belt on a pack.  I like that with a simple adjustment my umbrella will attach to the pack and I won’t have to carry it.  If I had to carry the umbrella I would not be bringing it.  As an aside, I want to try the umbrella as anytime I wear rain gear I end up sweating so much that I am soaking wet anyway, so the rain gear is kinda useless for me.   From what I read, hikers who have umbrellas love them.   We shall see.

What I am not crazy about is that I don’t have smaller side pockets.  This may not be a big loss, but I am used to them and I do/did find them handy.  I am not crazy about the front pack for carrying water bottles and other stuff.  It looks like it hangs down in front too much.  I like to be unobstructed in front.  I think.  That being said, I do like a front pack.  I have always used one in some fashion, be it a fanny pack or what I currently have now from http://www.ribzwear.com/.  I rarely use them for water, but instead for snacks, a bandana or two, TP, sunglasses, and other small things I would like to get to throughout the day.  I am going to try his front pack, but I suspect I’ll likely stick with my own if I am honest.

I also don’t like that I don’t have a place for my water bladder.  I used to never use one, but once I did it makes a huge difference.  A water bladder typically holds two or more liters of water and has a tube with a bite valve on the end that you can attach near your head for easy access to water throughout the hiking day.  I’ll see what I can figure out there.  Finally, I am bit concerned about weight shifting with the three barrels.  It appears they only attach to the frame at two points, so it seems to me that they may flop around a bit if not packed right.  I am fairly certain I am wrong in that assessment however, as it is based on pictures only at this point.

Pack ships next Monday.  Then I’ll have 30 days to figure this out.

-Seven

Google Chromebook

So, this morning I am testing out my new Chromebook.  I bought the Acer Chromebook 11 which came with 100 gig of Google Drive storage for free. Total cost is less than $200. The purpose of the Chromebook is going to be to put it in a bounce box and every few weeks use it to upload all my photos and video to Google Drive.  A bounce box is a box that you mail to yourself.  On the trail this can be very helpful as you can bounce box to yourself down the trail computers, charging cables, a set of clean town clothes, etc…  This way you have some stuff you may need, or want, but you don’t have to carry it with you all the time.  So the point is you determine where you will be in a week or two weeks or more and then mail the box to that location with instructions to:

“Hold for thru-hiker, Scott Edwards.  Expected arrival date of xx-xx-xxxx.  Phone number xxx-xxx-xxxx.”  

Once I get the bounce box, I’ll need a wifi connection and then I’ll be able to upload all my pictures, notes, etc.  I’ll also be able to update the blog if I have not done so.  Then at home, if space becomes an issue, Leslie could download them to our hard drive at home.  If not, we will just leave them on google drive until I get back and can sort and organize them.   Also, if I am craving a certain album or book that I did not previously load on my memory cards, I can have Leslie load them up to google drive and I can then download them to my memory cards.  🙂  Right now I use dropbox quite a bit and this might be my first step to moving everything to Google Drive.  

I uploaded 321 pictures from my camera this morning, a ton from my phone and it was simple.  Plug and play as it were.  I still have over 115 gigs of space available.  (Previous to the Chromebook purchase I apparently had 17 gig of storage on Google Drive and there were a few files there) I think this is going to work perfectly….well if I can now figure out how to post this.  The one thing I have noted already that I do not like about the Chromebook is that it appears to not have a delete key, only a backspace.  I did not realize how much I use the delete key in my typing.  Ah well, if that is the worst thing…..

Seven

Electronics

In the past the most electronics you would carry might be a camera.  Today that has been totally upended and you have numerous options, and some would say necessities.  Personally, I want to bring my phone as I will have service in most places on the AT and hope to share a lot of trip with Leslie via phone calls and sent pictures.  I also want to use a couple applications on my phone to make my trip a bit simpler, such at Guthooks’ AT application the Appalachian Trail Weather application.  From time to time, I would like to be able to listen to music, or perhaps a book on tape, as well as being able to read books via the Kindle application.  I would like to be able to take pictures and video.  I also want the ability to do voice recorder and then do voice to text translations.  This will make blog posts much simpler than typing on the phone’s keyboard.  Finally, I will need a way to power all of this stuff.  In thinking about all of this, I think I have decided on the following:

Phone:  Currently using an LG G4, but I will be upgrading before my trip.  I need a phone with a great battery and maybe a battery that I can swap out with a new one if needed.  I should also have the ability to minimize (shut down or delete) most applications to extend the battery life.  I will use this for phone calls, texts, voice to text translation, specific AT applications and internet posting.  Weight unknown as I don’t know what phone I will choose, but it will be somewhat minimal in terms of the weight to utility ratio.  At the moment thinking about the Apple iPhone 7 Plus or the LG v20.  I know I cannot swap out the battery on the iPhone, but I think that might be the only limitation to that model.  Need to make sure I can do the voice to text relatively simply on either phone, but suspect that is simply an application that I need to find.

Camera/Video:  I have a GoPro Hero 4 Silver video camera currently and need to learn more about how to use it.  It might be the only camera I take, however, it is so small it is somewhat difficult to use to take pictures.  I do have a clip to wear it on my chest to take some video of the trip.  It may become a dedicated video recorder for the trip.  I need to check into microphones so that I can add some running commentary to the video.  Weight 5.2 ounces with housing.

If I decide to take a standalone camera to take pictures, and I am 75% certain I will, I am looking at this Sony camera and extra lens.  Weight with extra lens 1 pound, 10 ounces.  https://www.amazon.com/Sony-16-50mm-Mirrorless-Digital-Camera/dp/B00QWRBZUE/  Mentally I am having a hard time justifying the extra camera and weight, and yet this is a once in a lifetime trip, so maybe I should just get over it.  An alternative would be to downgrade the camera to one of the point and click Panasonic models.  I could get away with about half the weight, but do give up some picture quality.

MP3 Player:  I think I will take a standalone MP3 player so I don’t need to run my phone for this purpose.  There are concerns of damage via weather or a fall or something else, so the more I can protect my phone, the better I think it will be.  So I bought this MP3 player for music and books on tape.  Weight with case less than 2 ounces and it is very small and will hold a 32 gig microSD card, bringing total capacity to 40 gigs of space.  That is a lot of music.  https://www.amazon.com/gp/product/B00VXMY262/

Portable Power:  I was considering a solar panel, however, the AT is known as the green tunnel, meaning I will be hiking through trees and forest a lot of the time, limiting the usefulness of a solar charger.  Further, since I will be going through so many towns, recharging won’t be an issue too often.  Given that, it makes a lot more sense to carry a portable charger rather than a solar panel.  I was looking at the Anker offerings  and ended up purchasing this model which should provide plenty of power for all my devices.  Weight 13.4 ounces.  https://www.amazon.com/gp/product/B01K6TA748/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

Safety:  Finally, I will likely carry a DeLorme Inreach SE satellite communicator.  The benefit of this device is that I can track and share my trip in such a manner that it will show up on a map on my website.   This will provide peace of mind to not only my wife, but my Mom.  Hi Mom!  🙂  Weight 7 ounces.  https://www.amazon.com/Delorme-AG-009871-201-DeLorme-inReach-SE/dp/B00BX7TJ2O/

——-

Electronics have become somewhat pervasive in our lives and it is very difficult to get away from them even in the wilderness.  I know in scouts this was always an issue (standard old school scout policy was no electronics on outings), and in the end I have changed my thinking to embrace electronics and what they can do for us.

However, I have three caveats for electronics.  The first caveat is to not become reliant on them.  This is a very real problem, such as using the GPS aspects of electronics for navigation.  If you do not know how to use a map and compass or other navigational techniques, correctly, and instead rely on electronics, eventually you are going to find yourself in a potentially life threatening situation when the electronics fail you.  My second caveat, which really applies to all gear that goes into the backpack, is weight.  Specifically, it is the weight to utility ratio and that ratio can be set a bit different for each person.  The ultra-light backpacker whose main focus is weight, is going to have a different weight to utility ratio than I will have, because as part of the utility aspects of a piece of gear I strongly consider comfort (both physical and mental).  My final caveat relates more to the leave no trace aspects of backpacking and relates to everyone else and the wildlife that I will meet on the trail.  If I am using electronics such as music, books on tape or a video of some type, I should be using headphones to negate the impact that my personal use of these items might have on others.

Mentally I can justify each item above, and equally as quickly I could make an argument to take nothing but a camera of some nature and possibly a cell phone for emergency use.  This is a very personal choice, and for me the deciding factor is the items above will make aspects of the trip more comfortable for me personally, and as such will increase the chance of completion.

 

The Big Three

I have already decided on my big three items.  The big three are shelter, sleeping system and pack.  I am working on more specific posts about each of these categories, with the advantages and disadvantages of the various choices within each category.  However, I will provide a short discussion of my choices in each category here.

For the shelter, I have settled on carrying my tent in the beginning, switching out to a hammock midway through June and probably back to the tent mid-August.  The main reason for this is the hammock tends to sleep cooler, and provides better air flow during the hotter months of the summer and I wish to give it an extended test on a serious backpacking trip.

For the sleeping system, I used to use a down filled mummy sleeping bag, but I hated it as I am a side sleeper and a mummy bag pretty much requires you to sleep on your back. I now carry a sleeping quilt instead.  It is similar to a blanket, rather than a confined bag and will allow any sleeping position.

For the pack, I prefer an external frame pack to an internal frame pack for a few reasons.  First, I sweat a lot and find the external frame packs a lot cooler on my back than the internal frame.  Second, I find it much easier to carry the weight of the pack on my hips with the more solid external frame, than the suspension built into the internal frame packs.  Finally, I love the pockets and panel zippers of the external frame packs over the more normal one large pocket of the internal frame packs.  I know exactly where everything is and can find my gear much easier.

The Big Three

Tent:  Taprtent Double Rainbow with extra poles so that it can be setup free standing.  Weight 3 pounds, 4.5 ounces.

http://www.tarptent.com/double-rainbow.html

Hammock:  Hennessy Hammock Hyperlite Asym Zip.  I might use this from mid-June through mid-August.  Weight 2 pounds, 4.0 ounces.

https://hennessyhammock.com/products/hyperlite-asym-zip

Sleeping Pad:   Therm-a-Rest NeoAir XLite Sleeping Pad with Therm-a-Rest  Universal Sheet.  Weight 1 pound, 2 ounces.

https://www.amazon.com/gp/product/B00PZL14EK

https://www.amazon.com/gp/product/B00AZVNEPC

Sleeping Quilt:  Enlightened Equipment Revelation.  Weight  1 pound, 2 ½ ounces.

http://www.enlightenedequipment.com/revelation/

Pack:  Jansport Carson 90 External Frame pack.  No longer available.  Weight 4 pounds, 13 ounces.

https://www.amazon.com/JanSport-90-Carson/dp/images/B0000AMLGJ

 

Clothing – Hiking Shirt and Long Sleeved Shirt

One thing I never really worried too much about was the fabric of my clothing while in the back-country.  In part because I was never gone for more than a couple of weeks, and when I was gone for that couple of weeks, it was at Philmont where a staffed camp was always within walking distance and in part it was because I loved everything about cotton, disliked the synthetics and could not wear wool.

However, for the AT, or any extended trip, I believe it is more crucial than ever to concern myself with fabrics for several reasons.  First, the more comfortable I can make myself during the day or night, the better chance I have to succeed.  Completion of this trip will be more about the mental aspects, than the physical (unless an injury occurs) and therefore the more comfortable I can be during the day/night, the better my mental framework.  Second, there will be times when I am on my own and need to stay warm and dry, so clothing choice can indeed have a health, safety and well-being impact.  Third, some fabrics tend to take on and promote smells worse than other fabrics.  If I was simply in the back-country for two weeks with others that were going to be in the back-country for two weeks, I would not concern myself with this aspect all that much.  If everyone smells as bad as everyone else, so be it.  However, the AT passes through a lot of civilized areas and even though the people in those towns may understand how bad a thru-hiker can smell, there is no need to revel in that and share with everyone around you.  In fact, I think attention to hygiene while on a trek of this nature is of concern from a health standpoint as well and will have more on that in a different blog post.

I have heard many times while getting ready for Philmont that cotton kills.  You’ll hear all sorts of self-proclaimed experts at backpacking say that, “remember, cotton kills.”  It is like the catch phrase for someone that really doesn’t know much, but knows at least that much.  I guess.  The comment comes from that fact that cotton dries very slowly when wet and if you get wet wearing cotton in cold conditions the cotton will whisk away the heat from your body and you can develop hypothermia rather easily.  There really is nothing worse than a wet cotton shirt in a cold mountain breeze.  However, I have always loved cotton.  The feel of cotton cannot be beat in my opinion, and the synthetics were always too, well, fake or something for me.  I am just not a fan of the feel of plastic against the skin.  So normally, I would take cotton shirts for backpacking.  I also tend to sweat a lot.  So the cotton shirts would endure a complete and total soaking each day of hiking, regardless of the weather.  This causes two things.  First, cotton does not dry easily, so upon reaching camp for the night, I would have to change my shirt and attempt to dry out the hiking shirt.  Sometimes by the next morning it would still be wet, other times it would be dry (in the Boundary Water or Isle Royale it was almost always still damp, but in New Mexico or Colorado, where humidity was much lower, it would be dry by morning).  The other thing about cotton is once it starts to smell (usually after the first full day of sweating in it) it would develop a funk that would become almost non-bearable.  The synthetics I have tried, polyester, polyester blended with elastane and polyester blended with spandex all dry a lot faster than cotton which is a plus, but develop a funk seemingly faster than cotton and ultimately worse than cotton.  Everyone said I need to wear wool.  It is warmer than cotton when wet, does not develop a funk like cotton or synthetic and better regulates body temperature.  My problem with wool is that my skin is very sensitive to it and generally speaking I have never been able to wear any wool without a complete layer under it to protect my skin against the itching.  While hiking this would defeat the purpose completely.  So I ordered my first Merino wool t-shirt.

Patagonia Men’s Merino Lightweight T-Shirt

I ordered this shirt and paid $69.00 for it.  That seemed like a ridiculous amount to pay for a t shirt, but I really wanted to try wool.  Upon unpacking it felt very soft in my hands.  Better than cotton, and I was optimistic that it might work.  As soon as I put it on I could tell that it would drive me insane with the constant subtle itching.  I took it off and back it went.

After that I posted on one of the facebook groups looking for suggestions.  I also re-read Andrew Skurka’s blog posts about clothing and wool looking for hints as to what might make this better.  I was hoping that a woolen blend of some nature might work for me.  I discovered that wool is measured by micron size.  The micron size is the diameter of the wool, and the smaller the micron size, supposedly the softer (and less irritating) the feel.  So I started to pay attention to micron size and the micron size of the wool in the Patagonia shirt was 18.9.  On facebook I was directed to Woolx and Smartwool.  I don’t recall if it was on Andrew’s site or in the comments on Andrew’s site or somewhere else, but the other option I was directed towards was Rab.  Determined to find a wool shirt that would work, I ordered one of each.

Rab Meco 120 T-Shirt

This shirt cost me $70, so the same price range as the Patagonia.  This is a blended shirt, 65% Merino Wool and 35% recycled polyester with Cocona.  Cocona is activated carbon from coconut shells and is permanently embedded into the shirt at the fiber level.  Cocona is lauded for many properties such as quick drying, temperature control against the skin and odor control.  Anytime you stray from 100% wool, you will introduce the properties of synthetic materials into the shirt…such as odor issues, slower drying and less temperature control, so the blending of this shirt with cocona to mitigate those issues is a plus.  I have worn this on training hikes, and I believe I have found my shirt.  It dries quickly, and resists odor very well.  I will continue to test this shirt, but most likely it will be my t-shirt and long sleeved shirt for the trip.  I could not find the micron size of this shirt, but it many respects it does not matter as the shirt does not bother my skin.  It is either the micron size or the blend of fabrics that makes this shirt bearable to me.

Smartwool Men’s PhD® Ultra Light Short Sleeve Shirt

This shirt cost $70 and was another blended shirt being 56% Merino Wool and 44% Polyester with a slight change in percentage for the mesh on the back of the shirt.  As soon as I tried this shirt on I noticed the overall body itchiness that I had with the Patagonia shirt.  I attempted to find out the micron size of this shirt, but it was not posted anywhere that I could find.  Back it goes.

Men’s Merino Wool T-Shirt By Woolx

I bought this on Amazon as the Woolx site only had this shirt in Black when I wanted to order.  By spring they will likely have a full range of colors available once again.  It was $49, so a nice savings there.  It is 100% Merino Wool, so I was very skeptical, but they had a full guarantee that this shirt won’t be itchy and I even had the option of washing it a few times before returning to give it a full chance.  The micron length of the wool is 17.5 microns, which is smaller than the others, so there was hope.  Out of the box it was soft in my hands and I was optimistic.  Upon trying it on, it did not itch. I will also keep this shirt and subject it to further testing.

So now I have two companies that might supply my top layers for my trip.   At the moment I think Rab will probably be my shirt of choice due to the blended nature of it and the cocona.  Wool does not dry very fast, so I believe the blended nature of the Rab shirt will likely give it faster drying properties than the 100% wool shirt which is a bonus.  The blended nature though could offset some of the odor control    properties of the wool, but since it contains the cocona, my hope is that it retains the best features of both worlds:  odor control, quick drying and temperature control.  Am I asking too much out of shirt?