How to Choose Base Layers

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Made from 100% merino wool, the men's Icebreaker 200 Oasis Half-Zip top layers effortlessly under any mid and outer layers for the ultimate cool-weather adventures.
Shop newer versionImported.
View all Icebreaker Men's Base Layer Tops| Best Use | Snowsports |
|---|---|
| Shirt Type | Partial-zip |
| Fabric | Merino wool |
| Sun-Protective Fabric | Yes |
| UPF Rating | 20 |
| Moisture Wicking | Yes |
| Quick Drying | Yes |
| Underwear Weight | Midweight |
| Sleeve Length | Long Sleeve |
| Gender | Men's |
| Sustainability | Contains ZQ merino wool |
| S | M | L | XL | XXL | XXXL | |
|---|---|---|---|---|---|---|
| Chest | 33-36 | 36-39 | 39-42 | 42-45 | 45-48 | 48-52 |
| Waist | 27-30 | 30-33 | 33-36 | 36-39 | 39-42 | 42-46 |
| Hip | 34.5-37 | 37-39.5 | 39.5-42 | 42-44.5 | 44.5-47 | 47-50.5 |
Measurements are stated in inches unless otherwise indicated.
CHOOSING THE RIGHT SIZE: If your body measurements are midway between two sizes, select the smaller size for a tighter fit or the larger size for a looser fit. If your body measurements result in different sizes, we recommend using your chest measurement for tops and your hip measurement for pants.
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[This review was collected as part of a promotion.] icebreaker US gave me this free product to try. I used this half zip on a recent backpacking trip in desolation wilderness, and honestly performed really well for me there. The temperatures dipped into the low 40s, and it wouldn’t have kept me warm on its own, but it served as a great base layer underneath a warmer shell. The icebreakers strength lies in its ability to keep yourself from overheating while exerting yourself, which made it great to wear while hiking. If you’re looking strictly for warmth, there’s warmer sweaters out there, but this will be great for the active person who wants something that wicks moisture well. Added a bonus of the Merino wool is that it didn’t smell at all after the backpacking trip!
[This review was collected as part of a promotion.] Icebreaker US gave me this free product to try. Went for a trail run this morning. It was chilly when I started and sunny when I finished—perfect weather for my Merino 200 Oasis LS Half Zip. I usually wear this with a moisture-wicking tee underneath for runs or when layering under my ski shell. This half-zip keeps me warm but never feels heavy or "soaked through" when I sweat. Best of all, Icebreaker merino fights off the stinks that you'd usually endure with high-output activities (or multiple days camping). I'm 6' and roughly 182 lbs, and the large fits perfectly. Not too snug, but form-fitting enough to feel athletic in. I'm a fan!
[This review was collected as part of a promotion.] The Merino wool layer was great for a variety of conditions. Whether that was lounging around at camp or hiking some of the high peaks in the Adirondacks it handled it all exceptionally. It was very comfortable with no chafing and was really soft. I had no problems with odor control even after wearing it for multiple hours on long hikes. It breathes well, keeps me warm when it’s chilly and cool if it’s a bit warm. I plan to use this as a layer during my upcoming snowboard season as well. I am a short, muscular build guy and the size large was a good fit. A little long in the arms but I’ve come to expect that in the things I wear. I’m sure it would be fine if you were about 6-8 inches taller than I am. Material stretches well and I couldn’t feel the seams which is always a huge plus. icebreaker US gave me this free product to try
[This review was collected as part of a promotion.] The Icebreaker Oasis Long Sleeve Half Zip is quickly becoming my go-to base layer and light top. The fit is snug without feeling restrictive, and it’s comfortable enough to wear all day. I tend to run warm, but this top balances insulation and breathability so I don’t overheat, even when I’m active. It works well on cool mornings, as a base for skiing, or layered lightly for hiking. I’ve noticed it stays fresh longer than synthetic layers, which is a big plus on multi-day trips. Overall, it’s versatile, comfortable, and dependable whether I’m outdoors or just lounging at camp. Icebreaker US gave me this free product to try.
[This review was collected as part of a promotion.] Icebreaker US gave me this free product to try and I enjoyed wearing it while exploring Telluride on the mountain bike during leaf peeping season. At the start of the ride at the base it was on the warmer side and the Oasis 200 did a great job of moisture management and keeping me comfortable during my nearly 90 minute climb. Cresting at around 11,200 feet it was much cooler and quite windy but the Oasis 200 kept me comfortable and warm especially at the start of the descent. The fabric dries incredibly fast, and was basically dry by the time I came off the descent, which still had some aerobic efforts in it. Like other reviewers I found the shirt to be a little on the shorter side, but for riding I appreciated the shorter length as it really layered well with my hydration pack and shorts. I’m 5’10 and around 170 lbs and the size large is perfect for me. Could have easily sized down to a medium though for a more compression fit.
[This review was collected as part of a promotion.] I received this product for free for testing. Overall I think this product is a great base layer or mid layer. It’s a secure and athletic fit. I’m a true medium and this fit well as a base or mid layer. For a base layer I would see myself using it for skiing and for a mid it’s perfect with a t shirt under and using this as a mid for a fall or winter run. Like I said it’s on the snug side but does a great job with moisture wicking and keeping me at the right temperature even when it’s sweaty. Overall I think this is a great piece and I would recommend it.
[This review was collected as part of a promotion.] For technical useage on rock and ice climbs, (frozen waterfalls) technical mtn climbing.
I really like the fit, feel and performance of this as a baselayer. I've worn it from house chores to runs and it performs wonderfully at either end of the spectrum. The quarter zip and wool makes it breathable and comfortable when working hard. This is a great option for anyone looking for a comfortable, do everything, merino quarter zip.
[This review was collected as part of a promotion.] The Oasis Long Sleeve Half Zip has been an amazing part of my wardrobe as fall comes around. This thing breathes incredibly well, so it handles all kinds of temperatures in the wet or dry really well. Even though sometimes merino can be scratchy, this material is really comfortable to! Can’t recommend it enough. Big thanks to icebreaker US, who gave me this free product to try.
I love this top. It's my 3rd one. I wear them all the time. They are my go to number one shirts for the office or out. Keeps me warm in cold offices as well as outside. They retain their shape even in the washing machine and hot dryer. No itch. Only negative--got a hole at the elbow on one sleeve when I rubbed up against a metal bolt sticking out of a chair arm. Because they are wool based and not poly, they can tear more easily but they are worth the fit and feel.