How to Choose Base Layers

Get ready for adventures in the cold with our warmest merino wool base layer yet. This supersoft REI Co-op heavyweight base layer top is made with 100% merino wool. It wicks sweat and dries fast.
Imported.
View all REI Co-op Men's Base Layer Tops| Best Use | Multisport |
|---|---|
| Shirt Type | T-shirt |
| Fabric | 100% merino wool |
| Sun-Protective Fabric | Yes |
| UPF Rating | 50+ |
| Moisture Wicking | Yes |
| Quick Drying | Yes |
| Underwear Weight | Heavyweight |
| Sleeve Length | Long Sleeve |
| Gender | Men's |
| Sustainability | Fair Trade Certified™ Factory From a Climate Label Certified brand |
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I wanted sun protection that didn't stink like a chemical factory after I finished a bike ride and this is it. While riding my bike on a hot sunny day, the shirt was not too hot-- it benefits from the breeze while riding and keeps you cooler. It does not smell after the ride too- I took it off and draped it over the back of my car seat and it dried and does not smell. I can wear it for another ride if I want. If you are a competitive rider, this shirt will add weight-- it's heavy compared to synthetic fabrics, but that was not an issue for me. It will also work well when riding during the winter too. Be aware, you'll want to hand-wash.


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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.

