KUIU Ultra Merino 145 Zip-Off Bottom Long Underwear Review

Have you ever wanted to wear long underwear on a cold winter day, but decided not to because you know you’ll sweat too much? Imagine having long underwear with side zippers that you could vent if you get to warm, or even remove completely without having to take off your boots or outer pants.

KUIU Ultra Merino 145 Zip-Off Bottom Long Underwear

Warmth
Comfort
Versatiklity
Weight
Ease of Care

Great Layering Piece

KUIU Ultra Merino 145 Zip-Off Bottoms can be vented or removed without taking off your boots, just like full zip rain pants, making them ideal for winter hiking and other snowsports.

Shop Now

KUIU makes a variety of zip-off long underwear bottoms for this exact purpose. While KUIU focuses mostly on hunters, these zip-off bottoms are also ideal for hikers, skiers, or really anyone who is active outdoors in winter. They’re also very reasonably priced and available in wool, synthetic yarn, or fleece to suit your preferences.

Ultra Merino 145 Zip-Off Bottom

If you’ve ever owned a pair full zip rain pant, like Marmot Precips, these KUIU long underwear zip-offs work the exact same way. They have side zippers along the outside of each leg and velcro in the waistband. You can unzip the legs partially to vent heat or unzip them all the way, open the velcro tabs at the waist, and pull them completely off without having to remove your pants or boots.

All of KUIU’s long underwear bottoms are boot length with a 26″ inseam, so they only go down mid-calf. I find that desireable because I mainly wear mine with high gaiters and winter hiking boots and my socks would get soaked with sweat if they were much longer.

KUIU makes the wool versions of their zip-off bottoms with a 90/10 wool and polyester blend called NuYarn that makes them more durable and reduces shrinkage. Traditional wool fabric is knit from single-ply yarns in which wool fibers are drawn into fine strands and twisted together for strength. NuYarn eliminates the twist in the yarn. Fibers are placed around a core and drawn out into a superfine fiber with zero twist. NuYarn uses a nylon core for added strength, hidden inside the fine merino-wrapped fiber. The resulting merino outperforms the world’s best ring-spun merino fabrics in almost every performance metric.

The KUIU Ultra Merino 145 Zip-Off Bottoms have a fabric weight of 145 g/m2 and weigh 7.3 oz in a size XL. They have flat seams and a gusseted crotch for agility, in addition to a “man-port”, so you can pee while you’re wearing them. You don’t feel the zippers on your skin when wearing them and they’re fairly thin, so they don’t bunch up under the softshell winter hiking pants I wear.

I only wear long underwear on very cold days, usually when temperatures are 10*F or colder. I run hot when I hike, so it’s nice to be able to remove the zip-off bottoms when the day warms up and I start to sweat. I’ve also found the 145’s very comfortable when worn as a sleeping base layer on overnights and I appreciate that they seamlessly fit right into my 3 and 4 season clothing systems.

The 145’s do take a little extra care when washing. It’s best to wash them cold with Woolite and not a harsh everyday detergent. KUIU does not recommend machine drying, so I just hang them and let them dry that way.

KUIU’s Ultra 145 Wool Zip Off Bottom can be removed without taking off your boots.
KUIU’s Ultra 145 Wool Zip-Off Bottom scan be removed without taking off your boots.

Recommendation

KUIU Ultra Merino 145 Zip-Off Bottoms can be vented or removed without taking off your boots, just like full zip rain pants, making them ideal for winter hiking and other snowsports. While they do require a little bit of extra care to wash, they’re a unique layering option for people who start cold and then warm up and want to delayer.  These KUIU zip-offs are such a simple idea, you have to wonder why no one thought of it before.

Disclosure: The author purchased this product.

Editor's note: Help support this site by making your next gear purchase through one of the links above. Click a link, buy what you need, and the seller will contribute a portion of the purchase price to support SectionHiker's unsponsored gear reviews, articles, and hiking guides.

Most Popular Searches

  • kuiu
  • zip off long johns

7 comments

  1. Love the video.

  2. Looks great. Starting to really look into companies like Kuiu, Mystery Ranch, and First Lite for hiking clothes and not just for hunting. The full zipper is a great idea because I am also quick to overheat so they would be very convenient. One more thing to add to the list.

    • I’m doing more “wilderness backpacking” these days off the crowded and beaten track and some of the gear and clothing from these companies makes a lot of sense for those more rugged conditions.

  3. Like what strippers wear, but with zippers instead of snaps?

  4. For years now I have been cutting into brand new long johns,and putting in a 6-8″light weight zip in the bottom of the legs so I can get them on and off over my boots.as you my know us kiwis always get around in shorts and long johns in the wet and cold.

  5. YKK side zips can be added to any legging (preferably sized up) to achieve a similar effect. I have used YKK’s 31” heavy duty zips on wool leggings.

  6. At some point it would be worthwhile to review the Pro Merio shirts and zip off long johns. The material is bonded merino to a synthetic shell. I’ve recently purchased a set and found the combination truly comfortable, warm, breathable and rugged. This new material raised the bar for me. I think you’ll like it if you try some.

Leave a Reply

Your email address will not be published. Required fields are marked *

Do NOT follow this link or you will be banned from the site!