Merino Zip-Off Bottoms: Function and Efficiency

Last week while browsing a few different forums I noticed more than one question surrounding the design and use of our Merino Zip-Off Baselayer Bottoms. Like they used to say in school, if one person has a question, then there are likely others wondering the same thing. The Zip-Off Bottoms have become one of my favorite layering pieces over the past year, so I’d like to make sure everyone is clear on how they work and why they were designed the way they are.


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The first thing that most potential buyers notice and question about the zip-off bottoms is the length. They are obviously different in that regard from traditional long underwear that ends around the ankles, and it’s a normal instinct for potential buyers to initially shy away from a product that appears to fit differently than what they’ve become accustomed to wearing for years. I’d be lying if I said that I didn’t have my share of eyebrow raising moments as Shaun catwalked the halls of the KUIU office in his mid-calf length baselayer bottoms during the developmental stages of the product. Fashion sense aside, the shortened length concept makes sense and works in the field. There’s really no reason to have a baselayer insulate the lower leg within the upper of the boot… that’s what socks are for. Furthermore, the beauty of the zip-off feature is that the user doesn’t need to remove his pants or even touch his boot lacing to add and/or remove this layer. Lastly, the garment weighs less without the excess fabric.


The functionality of the easy-on, easy-off design could not be better. Gone are the days where you tough out the bitter cold in the mornings to avoid having to basically change clothes later when the sun came up in order to shed my traditional long underwear. It’s not that we don’t have time on a hunt to take our boots and pants off and then put them back on again, but let’s face it… it’s an inconvenience that’s typically avoided until the heat of a baselayer bottom becomes completely unbearable. The zip-off bottoms change all of this. It’s a no-brainer to put them on in the morning when it’s cold, and it only takes about 15 seconds to remove them, put them in the pack, and continue with the day as soon as it gets too warm.


This image provides a better look at how the zip-off bottoms work.

A couple frequently asked questions are how does the zipper feel against the leg, and how do the upper closer tabs feel against the waist? The answer is pretty straight forward- you really don’t ever feel either of them. The size 3C YKK zippers are small and soft, and have an inner trim that closes off contact between the skin and the zipper teeth (detailed photo below). Though slight in size, these zippers have proven to hold up very well. We have yet to receive a single warranty claim against the performance or longevity of the zippers on the zip-off bottoms.


Next to skin side of leg zipper. Notice how no zipper teeth are exposed.

The upper velcro closure tabs are designed in a way that keeps all of the hook and loop material out of contact with the body. Additionally, there is almost no bulge or change in thickness along the waistband that would create an uncomfortable pressure point while wearing a pack waist belt over the top.


The velcro side tabs create a very smooth and comfortable transition between the front and rear panels.


I hope this helps clear up some questions surrounding this baselayer piece. The Merino Zip-Off Bottoms are undoubtedly KUIU’s most under-the-radar innovations of the past year.

GIVEAWAY (Update Below)


JAMES PARMER, your name was drawn as the winner of this Giveaway. I have emailed you with instructions. Thank you to all who took the time to comment on this post. Your responses are invaluable to those who come across this post down the road while researching this product.

On a side note, it was brought to our attention yesterday that the previous SUBSCRIBE feature used for this blog has sent a some unrelated emails to our readers. We immediately deactivated and removed the problematic subscription provider, and have replaced it with a new one that will not send any unwanted emails. Thanks to those of you who notified us of the issue.

Todd Harney

72 thoughts on “Merino Zip-Off Bottoms: Function and Efficiency

  1. Good on you guys for focusing on the details in making incremental improvements to this kind of layer. I have some old Helly Hansen versions that are similar, but they’re a) not merino, b) the side zipper chafes against your skin and c) they’re made for ski boots, not hiking boots. I don’t have any of yours yet, but they’re definitely on the list.

  2. This is an outstanding addition to something that has been used by many, for many years. It’s just what I would expect from KUIU. You guys think of everything and leave no detail untouched. If I don’t win a pair I’m going to buy one…. Keep up the great work, Scott

  3. I think these bottoms are exactly what I am looking for. My question is whether the 210 Merino when paired with the Attack pant will be warm enough for my late October/ early November elk hunt in Montana. I am looking forward to putting KUIU through its paces this year. Love the product and thanks for posting the Merino zip off bottoms discussion.

    • The 210 bottoms paired with Attacks is pretty warm, and should be fine for you hunt. Rain pants over the outside to block the wind while stationary could come in handy too.

  4. I don’t own a pair of these yet, but now I see how the full zip off function works. I can’t wait to add a pair or two to my collection before my late season cow hunt. Keep up the great gear.

    • Good question. They’re fine, since they stretch pretty well you’re really not pulling the zipper up against your leg. You can hold the zipper 1-2″ away from the leg as you zip them. Hair doesn’t go into the zipper at all while closed up.

  5. I have pair of the 210 zip offs , I used them all spring predator hunting in Oregon . I Love how easy it is to start my day off warm and comfortable then when the temperature gets warm I can remove the base layer with out taking off my boots , stuff them in my Ultra 3000 hunt all day till it gets cold again and put them back on .

  6. I have both the 145’s and the 210’s. I was a little skeptical at first about the length and feeling the zippers. The skepticism was gone after using them the first time. Never noticed the zippers or the velcro at the top. The shorter length worked well, even when wearing 14″ pac boots. I was still able to remove them without removing or loosening my boots. Huge bonus. Great product!!!!

  7. Great product. Thanks for the change with the subscribe provider, they were getting pretty annoying with their “we think you would like….” Thanks again and keep up the great post and products

  8. Thanks for the explanation Todd. I’m guilty myself of buying them trying them and not giving the benefit of the doubt and retuned them not knowing the above explanations you talked about. I will definitely reconsider trying them again as it all makes perfect sense now.


  9. I work as an aquatic fisheries technician and I spend 90% of my day in chest waders. I have been searching for a pair of pants that I could wear that would keep me warm in cool water but also dry fast when walking and sweating in the non-breathable waders. I am currently wearing classic ‘quick dry’ pants. I am wondering if the merino zip-offs would fit this application? I had thought about wearing my ice breaker 200 long underwear but think they might be too warm. Any thoughts?
    Thanks for proving a forum like this to ask these types of questions.

  10. I hadn’t notice that the bottoms had zippers and could be taken off with your booths on. That is an awesome feature and they will be first on my list to get.

  11. I started using Kuiu Base Layers a couple years back. The bottoms I bought and still use were the heavy weight. They are very warm and have lasted a couple seasons so far. At that time taking them off was different in how tight the lower leg was. I even put my thumb through the material taking them off. I finely figured pulling them off like socks worked better and faster. 2014 new style bottoms with side zippers ?? They work great and are still as warm as can be. Thanks for still keeping us warm on the stand and in the Hunt. Good Luck

  12. I have the 210 bottoms and love them, I wore them during a spring turkey hunt and they kept me warm sitting on the ground waiting for a big tom. At the end of the day when the sun was blazing I simply unzipped and cooled off instantly, great innovation!!

  13. I have the long john style and two pair of the new ones. Gave the old ones to my son. “Gee thanks” ,he said. He has not seen the new style yet. Ha ha, I’m such a good dad. I won’t go back to the long john style. My whole family knows not to by anything else but the Kuiu brand Marino Zip off Bottoms. Way to go guys. I love them.

  14. Been wanting to try these, just not sure which pants (top layer) I can also remove over my boots. Might work best with just my Yukon rain gear on top!

  15. I just purchased a pair of the 210 merino bottoms after a lot of research and trying other styles. I agree, that when they arrived I was skeptical. I didn’t realize the benefits of their unique design until they were on and the features utilized. These are well designed and built by mountain hunters for the mountains. Thanks again and keep up the innovation kuiu!

  16. I have both the 145’s & the 210’s and I won’t go on any hunt without them! Easy on and off depending on the temperature without taking off my boots!

  17. I usually roll without base layer bottoms for the exact reason you described, stuffing long underwear into or over boots is annoying. Neat product, that idea would be perfect for skiing as well.

  18. Really appreciate the picture of the pants fully unzipped and open…wasn’t until I saw that, that I fully understood how you could take these off and on without having to remove boots and pants and get fully undressed. Maybe I’m slow, but the pics really helped.

  19. I’ve never used a product like this.. How do they fair under those emergency mud blowing situations when the closest tree for privacy seems like miles away? I usually use a union suit for camp with button down ass flap just in case for when those camp meals kick in and twist your guts, I’m all about easy access.. If you know what I mean.

  20. Very interesting concept! It all makes sense, so I’ll definitely be checking these out the next time I stop by the showroom.

    P.S. – Thanks for resolving the unwanted subscriber emails!

  21. I can verify there is no rubbing from the zipper the the zipper has been very durable. I have the 145 and they are tight which I don’t mind but I have wondered more than once if the zipper would hold as I zipper them over my legs.

  22. Great article! I have to admit, I was one of the few in the back of the class that was curious but wasn’t asking the question about the details. I do still love my first generation 210’s for all day winter use. THANKS TODD.

  23. These are awesome. Easy off is a big bonus. I have a large and extra large in the 145. When its real cold I put the XL’s over the larges for a mini layering system. works great and I get a little more warmth then the 210’s. One of my favorite pieces from KUIU.

    • I am looking forward to trying out my new 210 base layer in Alaska’s Brooks Range on a Caribou/Wolf hunt next month…when I discovered KUIU gear, especially the zip off base layers, my first thought was…I wish I’d thought of that! For way too many years of hunting WY and MT back country, I suffered with being too cold or too hot (seldom just right) with “traditional” base layers, not counting the inconvenience of making the proper clothing adjustments during the day!

      Thanks, KUIU for thinking outside the box…it’s about time!

  24. I used a pair this past spring when the temps would change drastically throughout the day. They are easy to take off without having to completely undress. I don’t miss having to lay out a jacket to stand on while completely disrobing to shed a bottom layer. Once I put them on and started hunting I completely forgot about the zipper and waist closure, even while wearing a pack. No chaffing or hair pulling and mine are a snug fit. It does take a little practice to put them back on, but once you’ve done it in the field a couple of times it’s very quick and easy. I love them!

  25. I would love to see the Army adopt these. Im allways wet when the sun goes down. Imagine transitioning to these when shedding wet cloths and having to settle in. Could hop in a bag with them too.

  26. I do not own these…yet. I will get some soon. I think it is a great idea. It is inconvenient to have to stop and take boots and pants off when it warms up in order to get your baselayers off. I hope they are as comfortable as advertised.

  27. I have a few KUIU products and you guys do think outside the box. I have been looking for something like these for a while. I like the length and that extra material in your boot is unnecessary. Can anyone ever say they were cold from the ankle to the where a boot ends? Keep up the good work.

  28. This Awesome!! Here in the deep South we get cold mornings and a good bit of warm up and this would be perfect for that. Way to go with the design!!

  29. I have a pair of the 145’s. I had the same initial thought about the length when I first put them on, but then realized why. Just like all their products, everything is always well thought out.

  30. I must say that I initially had my reservations about the length, especially as a tall guy. The more I think about my use especially when hunting, the more I like the idea of the shorter zip-offs for dawn/dusk.

  31. I have been wanting to try these out for ever. Seems like a great idea to me. Im gonna try and order some for this season. Seems like they would be an okay/cheaper alternative to the down pant

  32. I usually go without a bottom layer because I hate being hot in the middle of the day and am too impatient to take the time to undress. Add these to the many kuiu items that I need to try out.

  33. Fantastic baselayer. I’ve worn my 210 bottoms with chinook pants all day in low teens and never felt the need for more warmth. Great combination!

  34. I hadnt received my ultra 145 merino bottoms prior to my mid-season elk hunt and mule deer hunt, but they never left my body during my 14 day late season Ibex hunt, except when it was in the low 80’s. However, when the weather turned and it snowed two and a half feet with the wind blowing 60 mph on the knife ridges they stayed on days at a time. I went Rambo commando, guess what… My base layer smelled like roses… Well maybe not that nice, but my tent buddy never complained about my smell. His Air Force synthetics on the other hand were rank. Don’t tell him or uncle Sam I said this… Aside from the actual material and its anti microbial properties. They were super convenient to take on and off comapred to my “old fashioned” long johns….

    These things I found out have a zipper, i’Ll be damned!… Didn’t notice till days later… I’m just joshin around, on a serious note, that is how noticeable the zipper and velcro is running down your whole side. It is nonexistent, outta sight and mind, as they say. But come brunch time, when you feel that sun after you’ve been hiking and stalking for hours before first light and the sun just woke up and it feels like a Tucson at noon, that, my friend, is when you love the zippers and Velcro. Same goes for when the wind starts to blow on a knife ridge and you are glossing, you jump up and zip them bad boys on in a hurry. Instant smile. In a big nutshell, these have changed the dynamic of regulating body heat, what used to be a chore, kuiu has functionalized into a subconscious…. Well, maybe not that easy but you get the idea!

  35. Just what I have been looking for. It makes such common sense. We Bow hunt for elk at high elevations, it’s cold in the early am and really hot mid day…we are always stopping to peel off upper layers but never do lowers. It is such a procedure and so time consuming. Evening sees the temp drop dramatically and necessitates another drawn out exchange. These base layer problem solvers are cutting edge functionality…good work as always…practical and smart. Can’t wait to experience these with my new Attack pants I received on fathers day…..September is calling. Thanks for being real Kuiu “Gritty” men.

  36. I just joined the KUIU club and got my first items in the mail this week. Now I’ll have to start convincing the Mrs. that its time for a second order. I get hot so easily once the sun comes up, that this would be the perfect solution. I usually forgo the bottom layer and freeze the first few hours because of the inconvenience of taking them off. This looks like a great idea.

  37. Very comfortable, I really like being able to take them off without removing my boots. I used to just suffer through being cold in the mornings.

  38. Todd – very interested in adding these to my arsenal for my later season hunts this year. I’m concerned about the sizing of the calf hole however, as I’m guessing my 19″ calves will try to drag these down and perhaps make then feel like they’re either falling down the whole time or way too tight. Thoughts?

    • Shaun Ayers has 18″ calves and they work for him. Lots of stretch especially in the 145 weight. Shoot me an email for more info on how they might fit you or what we can possibly do to accommodate.

  39. Interesting take on a base layer. Never seen one that zips off like this. I love merino wool though. Will have to give these a look.

  40. Just received mine a couple of weeks ago. I think they are going to be great. Can’t wAit to have them on the side of a mountain.

  41. Great design. I will say they look a little funny at first but it’s all about functionality which is where they excel! Awesome product.

  42. Best base layer by far! It is innovation and designs like this, along with input from their customers that allow them to make such amazing gear that help us hunt longer and focus on our tasks on the mountain and not the small things! Thanks Kuiu.

  43. I love the design of these, i have always battled my upper socks getting soaked because my baselayer with my socks and insulated boots was just to much. I also think the zip on/off function is great, i am that guy that leaves in the dark to walk in. Awesome design, excited to order some.

  44. Face palming innovation.

    Beyond the feeling of wasting valuable time while removing everything down to my skivvies, I absolutely hated (now past tense, as I’ll buy two pair whether I get the giveaway or not) unlacing my already-settled-in feet just to remove my base layer. It’s impossible to get your boots laced back up to exactly the same position with the same feel, especially because the base layer was part of that feel.

    Thanks, KUIU

  45. it is perfect for purpose, its a layering piece. i can drop pants and add this layer quick without having to take off boots and possibly get feet wet plus my 145’s pack up to minimal size. innovative and effective that’s why i buy KUIU!!!


  46. I am looking at purchasing this base layer for an hunt, but I am a bit worried the XL will not fit. I have a 40″ waist. I wear xl in most other pants or shorts. Any thoughts on a XXL?

    • Hi Kevin,

      Give the XL a shot, it’s sized to fit your waist measurement. With the amount of stretch these bottoms have, you should be plenty comfortable in them. Good luck on your upcoming hunt!


    • Mainly because there are a lot of people like you who want it. The demand is simply higher than the supply. With that said, people who place backorders tend to get their gear fairly quick these days. We fill LOTS of backorders weekly, and many times shipments come in and ship out to customers on backorder without quite reaching “In Stock” status. If you don’t have a backorder for what you want, then you’d think we never got it in- meanwhile hundreds of units are being shipped daily to customers who did place a backorder.

  47. I have 2 pair of these and they are comfortable and warm. Don’t really notice the short legs. About removing them in midday, what do you do about underwear when you take them off? Zip-off shorts too? Don’t want to wear 3 layers on the bottom if I may need to put on some raingear(which would be 4 layers). Boxer briefs are great when it’s not too cold out.

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