This 100% merino wool base layer top from REI Co-op is built for adventure. The breathable, ultrafine wool naturally resists odors and pilling, while flat seams stay comfortable against the skin.
Ultrafine 185 g/m² merino wool offers a soft feel without any itchiness. It naturally breathes, wicks sweat, dries quickly, and resists odors and pilling. The half-zip front helps with venting, and the standing collar and chin guard add protection.
Key Features
Best Use
Multisport
Shirt Type
Partial-zip
Fabric
100% 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
Highlights
Ultrafine 185 g/m² merino wool offers a soft feel without any itchiness
Made with 100% merino wool that naturally breathes, wicks sweat, dries quickly, and resists odors and pilling
UPF 30 sun protection
Half-zip front helps with venting; standing collar and chin guard for protection
Flat seams and merrow stitch construction reduce chafing
Underarm gussets allow full range of movement
Semifitted to hug the body for optimum performance
Locker loop makes it easy to hang this to dry or just keep it off the ground
Machine wash warm, gentle cycle; use wool wash product; do not twist or wring; remove promptly; do not bleach; tumble dry low; cool iron; dry cleaning not recommended
Made of wool sourced according to third-party animal welfare standards adopted by REI Co-op brand
Made in a Fair Trade Certified™ factory
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
Materials & care
Machine wash warm, gentle cycle; use wool wash product; do not twist or wring; remove promptly; do not bleach; tumble dry low; cool iron; dry cleaning not recommended
How to use
Which material is best?
Wool: highly moisture-wicking and odor-resistant
Synthetic: durable and less expensive
Silk: soft and lightweight for casual activities
Match the temp to the trek
Lightweight layers: best for moderate to cool temperatures
Midweight layers: best for cold temperatures
Heavyweight layers: best for below-freezing temperatures
Find your fit
Must be close to skin to efficiently wick sweat; should fit comfortably snug
Base layer is for moisture control; your mid layer is for warmth
Better gear is built together. 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.
