REI Co-op Merino 185 Long-Sleeve Half-Zip Base Layer Top - Men's

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Color: Mountains Falcon Brown
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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 is Climate Neutral Certified; as we work to actively reduce our footprint, we measure annual carbon emissions and purchase an equivalent amount of verified carbon credits
  • Made in a Fair Trade Certified™ factory


View the REI Co-op Merino 185 Product LineView all REI Co-op Men's Base Layer Tops

Technical Specs

Best Use


Shirt Type



Merino wool

Sun-Protective Fabric


UPF Rating


Moisture Wicking


Quick Drying


Underwear Weight


Sleeve Length

Long Sleeve




Fair Trade Certified™ factory

From a Climate Neutral Certified brand

Size Chart

XSSMLXLXXLXXXL24 IN Waist26 IN Waist28 IN Waist30 IN Waist31 IN Waist32 IN Waist33 IN Waist34 IN Waist35 IN Waist36 IN Waist38 IN Waist40 IN Waist42 IN Waist44 IN Waist46 IN Waist48 IN Waist50 IN Waist
Chest3536 - 3839 - 4142 - 4546 - 4950 - 5354 - 57
Sleeve Length3333.53434.53535.7536.5
Waist27.528 - 3032 - 3436 - 3840 - 4244 - 4648 - 502426283031323334353638404244464850
Hip33.534.5 - 36.537.5 - 39.541 - 4344 - 46.547.5 - 50.551.5 - 54.53233.534.536.53737.538.539.540.2541434446.547.550.552.554.5

Sizing Notes

Measurements are stated in inches unless otherwise indicated.

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.

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