How to Choose Base Layers
REI Co-op Merino 185 Long-Sleeve Half-Zip Base Layer Top - Men's
$49.83Compared to $89.95*Save 44%
Soft and breathable, the ultrafine merino wool of the naturally odor-resistant men's REI Co-op Merino 185 long-sleeve half-zip base layer top is ideal for sweating on the trail—and sleeping in a tent.
- Ultrafine 185 g merino wool offers a soft feel without any itchiness
- Made with 100% merino wool that naturally breathes, wicks away sweat, dries quickly and resists odors, making it an ideal multiday trip companion
- UPF 30 sun protection
- Half-zip front helps with venting; standing collar and chin guard for protection
- Flat seams and merrow stitch construction eliminate chafing
- Underarm gussets allow full range of movement
- Designed to hug the body for optimum performance
- Weight: 8.5 oz. (size Large)
- Machine wash warm, gentle cycle, with wool wash product; do not twist or wring; remove promptly; do not bleach; tumble dry low; dry cleaning not recommended
- Field-tested on its own and as a base layer while hiking, running, rock climbing, cycling, skiing and camping in diverse climates across the U.S.
- REI Co-op brand is certified to The Climate Label; we actively fund efforts to reduce carbon emissions across our business and support climate projects around the world
- Made in a Fair Trade Certified™ factory
Imported.
View the REI Co-op Merino 185 Product LineView all REI Co-op Men's Base Layer Tops| Best Use | Multisport |
|---|---|
| Shirt Type | Partial-zip |
| Fabric | Merino wool |
| Sun-Protective Fabric | Yes |
| UPF Rating | 30 |
| Moisture Wicking | Yes |
| Quick Drying | Yes |
| Underwear Weight | Lightweight |
| Sleeve Length | Long Sleeve |
| Gender | Men's |
| Sustainability | Fair Trade Certified™ factory From a Climate Label Certified brand |
REI Co-op Clothing - Men's
| XS | S | M | L | XL | XXL | XXXL | 24 IN Waist | 26 IN Waist | 28 IN Waist | 30 IN Waist | 31 IN Waist | 32 IN Waist | 33 IN Waist | 34 IN Waist | 35 IN Waist | 36 IN Waist | 38 IN Waist | 40 IN Waist | 42 IN Waist | 44 IN Waist | 46 IN Waist | 48 IN Waist | 50 IN Waist | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chest | 35 | 36 - 38 | 39 - 41 | 42 - 45 | 46 - 49 | 50 - 53 | 54 - 57 | |||||||||||||||||
| Sleeve Length | 32 | 32.5 | 33 | 33.5 | 34 | 34.75 | 35.5 | |||||||||||||||||
| Waist | 27.5 | 28 - 30 | 32 - 34 | 36 - 38 | 40 - 42 | 44 - 46 | 48 - 50 | 24 | 26 | 28 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 38 | 40 | 42 | 44 | 46 | 48 | 50 |
| Hip | 33.5 | 34.5 - 36.5 | 37.5 - 39.5 | 41 - 43 | 44 - 46.5 | 47.5 - 50.5 | 51.5 - 54.5 | 32 | 33.5 | 34.5 | 36.5 | 37 | 37.5 | 38.5 | 39.5 | 40.25 | 41 | 43 | 44 | 46.5 | 47.5 | 50.5 | 52.5 | 54.5 |
| Inseam | 32 | 32 | 32 | 32 | 32 | 32 | 32 | 32 | 32 | 32 | 32 | 32 | 32 | 32 | 32 | 32 | 32 | 32 | 32 | 32 | 32 | 32 | 32 | 32 |
Sizing Notes
Measurements are stated in inches unless otherwise indicated. Size chart values represent body measurements, not garment measurements.
SHORT: Some pants are available in short sizes, which generally means an inseam that is 2.5 inches shorter than regular sizes.
TALL: Some pants, shirts, jackets and parkas are available in tall sizes, which generally means an inseam that is 3 inches longer and a rise that is 1 inch longer, a shirt or jacket body that is 2 inches longer, a parka body that is 2.5 inches longer and sleeves that are 2.5 inches longer than regular sizes.
Capri or cropped pants have an intentionally shorter inseam—reference the technical specs instead of this chart.
Inseam is measured to the floor.
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From feedback to field testing, all of our gear is dialed-in by REI Co-op members. Their adventures informed every stitch and detail—making for better, longer-lasting gear.
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Most Helpful Favorable Review
Super comfy but questionable durability
Tonytonetone2 years ago
I have always loved rei co-op as a brand just as much as the store itself. I’ve always been satisfied with the quality and longevity their products have given to me particularly on my day to day as well as my outdoor outings. Now before I go into the bad, let’s start this out with the good. I absolutely love their merino wool products. I’ve had a few of them that were gifted to me years ago that lasted some of the more enduring hikes as well as the toughest job sites where I had needed the warmth of wool. I recently bought another pair of base layers and haven’t been able to wear them due to the heat and now with the heat subsiding and the mornings getting frosty I’ve had the luxury of wearing these for the past week at work tucked beneath my actual work jeans, shirts and jacket and they’ve been extremely comfortable and I’ve forgotten that they were on. Mind you these haven’t seen the light of day as they’re never exposed during work, with the exception of the collared portion of the shirt. With that said I’ve noticed that the hem at the front of the shirt has a finger tip sized hole in it and it hasn’t even graced daylight let alone touched anything. How does something that hasn’t been worn a week after owning it for two months start tearing under light use at work? What gives REI? Did the quality I’ve come to know and love disappear in the last 8 years? I’m sorely disappointed in this shirt as I haven’t even hiked in it which was the sole purpose of purchasing it. Would I recommend this to anyone? Probably not especially if it’s $90 and can’t survive 4 days of moving packages at work let alone on a mountain trek. My last pair was a trooper and didn’t start tearing until it’s fourth or fifth year. I’m not sure if I could recommend it beyond the comfortability, especially since it’s advertised as enduring the trek. 4/5 for its comfort and warmth, I hope rei gives some insight as to how such an expensive article of clothing couldn’t take the heat or to remedy the situation altogether.
Tonytonetone
Rancho Cucamonga, CA
25 people found this review helpful
Most Helpful Critical Review
Not comfortable and irritating stitching.
Brendan3 years ago
It’s warm, but the stitching in the neck gave me a raw spot after only a few hours on the trail. It’s also a little itchy on the skin.
Brendan
Los Angeles ca
6 people found this review helpful
Customer Images
Ski bum
Received free product
Petaluma, CA
Super Comfortable & Lightweight Base Layer
4 years ago
This Merino wool base layer is extremely comfortable and super lightweight. It has a really tight weave (see pics below) and is soft. I found myself rolling it up and packing it for early morning MTB rides and evening hikes when it got cooler outside (Tahoe area). Easy to fit into zip pockets in backpack or even hydration pack. It was great for temps in the 50's with just a t-shirt under it. It is warm & wicked well when I started to sweat from the biking/hiking. I think it will be really nice for skiing, when you go from cold on the lift to hot/sweating during your run...looking forward to that test! I'm about 170lb, 42 inch shoulders, 33 inch waist and L fit me well with enough room to move. Half zip was nice addition, and I zipped it when I was chilled, and unzipped it when warmed up.
Age:55–64
Weight:150–175 lbs.
Height:5'10"
Yes , I recommend this product
MO BigDawg
Received free product
Warrensburg MO
Solid Cold Weather Base Layer
4 years ago
For those who enjoy the cold, this is a great choice of a base layer. The Merino wool is very soft. Thickness is just right for me, not too thick. It suits me well for the sub zero Midwest winter days, and more importantly for me, a good base layer on long motorcycle trips. There are two minor drawbacks for me, or otherwise it would have received 5 stars. For me the front zipper is too long, I would prefer it about 2-3 inches shorter. The other drawback is I wish it was about 2 inches longer, I know I have a long torso, so the extra length would have been nice.
Age:55–64
Weight:250–275 lbs.
Height:6'3"
Yes , I recommend this product
Tonytonetone
Rancho Cucamonga, CA
Super comfy but questionable durability
2 years ago
I have always loved rei co-op as a brand just as much as the store itself. I’ve always been satisfied with the quality and longevity their products have given to me particularly on my day to day as well as my outdoor outings. Now before I go into the bad, let’s start this out with the good. I absolutely love their merino wool products. I’ve had a few of them that were gifted to me years ago that lasted some of the more enduring hikes as well as the toughest job sites where I had needed the warmth of wool. I recently bought another pair of base layers and haven’t been able to wear them due to the heat and now with the heat subsiding and the mornings getting frosty I’ve had the luxury of wearing these for the past week at work tucked beneath my actual work jeans, shirts and jacket and they’ve been extremely comfortable and I’ve forgotten that they were on. Mind you these haven’t seen the light of day as they’re never exposed during work, with the exception of the collared portion of the shirt. With that said I’ve noticed that the hem at the front of the shirt has a finger tip sized hole in it and it hasn’t even graced daylight let alone touched anything. How does something that hasn’t been worn a week after owning it for two months start tearing under light use at work? What gives REI? Did the quality I’ve come to know and love disappear in the last 8 years? I’m sorely disappointed in this shirt as I haven’t even hiked in it which was the sole purpose of purchasing it. Would I recommend this to anyone? Probably not especially if it’s $90 and can’t survive 4 days of moving packages at work let alone on a mountain trek. My last pair was a trooper and didn’t start tearing until it’s fourth or fifth year. I’m not sure if I could recommend it beyond the comfortability, especially since it’s advertised as enduring the trek. 4/5 for its comfort and warmth, I hope rei gives some insight as to how such an expensive article of clothing couldn’t take the heat or to remedy the situation altogether.
Age:25–34
Weight:175–200 lbs.
Height:5'8"
Yes , I recommend this product
The_Chris
Received free product
Silverdale, WA
Outdoor Adventure Ready
4 years ago
The REI Co-op Merino 185 Long-Sleeve Half-Zip Base Layer Top is a solid merino base layer. I'm 6'-1" tall and 225 lbs. The XL size fit me very well. A fit feature I appreciated was the torso and arm length. When I reach above my head or extend my arms I don't want bare skin on my lower back or wrists exposed to weather. The REI Co-op Merino 185 Long-Sleeve Half-Zip Base Layer Top provided this coverage. The feel next to the skin was what you'd expect from merino wool - not scratchy. The half zip is a nice feature for when the temperatures start to rise and you'd like a little air flow. I do recommend this product for anyone in the market for a merino wool base layer.
Age:55–64
Weight:225–250 lbs.
Height:6'1"
Yes , I recommend this product
MountainHerb
Received free product
Los Angeles
Great base layer
4 years ago
Quarter zips are usually my go to just based off the extra zipper space. It makes it earlier to take off and put on. The material is great as it doesn’t seem to trap in any bad odors. It keeps you feeling cool in the warm days and warm in the chilly nights. The sleeves are perfect, something I find long sleeve shirts with shorter sleeves or excess material. Theses are the perfect length. Maintenance wise it is easy to care for, just wash and dry (air dry is best) may take a little longer but worth it. Doesn’t shrink or fade. The blue one I have has not faded and has kept its nice color. I’ve put it to test while hiking, walking around the neighborhood and even mountain biking. It’s has really held up. Whether I am wearing it out or throwing it into my riding bag it’s a Kepler for sure. Did I mention it’s light, also very packable.
Age:25–34
Weight:150–175 lbs.
Height:5'7"
Yes , I recommend this product
Shannon
Albuquerque, NM
Not durable
8 months ago
Bought it two weeks ago. Wore it once. Developed holes after first wash and dry cycle
No, I do not recommend this product
solo
Not durable at all.
7 months ago
Never worn and holes in it from washing once on delicate with Nikwax and air-dried.
No, I do not recommend this product
Brian
Received free product
Cottonwood Heights, Utah
Extremely soft thin wool base in a pleasant blue
4 years ago
Common with all my merino wool, this base layer is soft with no scratchiness. It is fairly thin so great for high activity on a cold day but may not cut it for a less active day. I did rate the overall fit at true to size, which I feel is only somewhat true. The trunk of the product is slightly looser than I would have expected yet the arms and shoulders are better fitting. My troublesome slightly longer than average arms fit well in this top and the length is quite a bit over the waist but not overly long. I would like it to fit a little closer overall to my skin which I expect from a small at my size. The tall neck is spot on for my liking, not too long to make me feel claustrophobic. There are 3 lines down the sleeve, a stitching, that I found a bit peculiar looking but they appear to keep the fabric from stretching so I hope it helps retain the shape of the sleeves which could be a concern as it is a fairly thin layer. The half zip if helpful with removing the top off without stretching the product out of shape.
Height:5'10"
Age:35–44
Weight:125–150 lbs.
IamV
SoCal
Highly function and very comfortable base layer
3 years ago
Wore this as a technical base layer for 10-20 degree weather. Kept me cool on the hike up and warm during the evening/nights. The zip was extremely functional with controlling heat. I had other layers/gear to help but there were moments where I used just the zip during the hike and that's all the adjustment I needed. The fit was really good and the color was nice.
Age:45–54
Weight:125–150 lbs.
Height:5'6"
Yes , I recommend this product
Flounder
Received free product
Bay Area, CA
Fits the bill
4 years ago
This is a great, versatile shirt. Not too warm, but gives you that essential cocoon layer. It breathes well. Its a little bit roomy, which is a nice change from some snug base layers I've worn before. The wool scratches a little, but softens up with the first wash. This is a critical piece of gear - and a great example of it.
Age:35–44
Weight:175–200 lbs.
Height:5'11"
Yes , I recommend this product
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