These heavyweight merino wool base layer bottoms are built for cold-weather adventures. The 250 g/m² merino wool feels soft against the skin without the scratchiness, naturally wicks away sweat, resists odors, and dries quickly.
A soft jacquard waistband sits comfortably on the skin with a low profile for easy layering, while a crotch gusset allows for ease of movement. The close-to-body fit supports optimum performance, and a locker loop makes it easy to hang these to dry or keep them off the ground.
Key Features
Best Use
Multisport
Fabric
100% merino wool
Sun-Protective Fabric
Yes
UPF Rating
50+
Moisture Wicking
Yes
Quick Drying
Yes
Underwear Weight
Heavyweight
Inseam (in.)
29 inches
Gender
Women's
Sustainability
Fair Trade Certified™ Factory - From a Climate Label Certified brand
Highlights
Heavyweight 250 g/m² merino wool offers a soft feel without the scratchiness
Made with 100% merino wool that naturally wicks away sweat, resists odors and dries quickly
UPF 50+ sun protection
Soft jacquard waistband is comfortable on the skin—and its low profile allows for easy layering
Crotch gusset is made for ease of movement
Close-to-body fit for optimum performance
Weight for size S: 7.6 oz. (216 g)
Locker loop makes it easy to hang these to dry or just keep them off the ground
Machine wash cold, use wool wash product, do not twist or wring, remove promptly; do not bleach; tumble dry low
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 cold, use wool wash product, do not twist or wring, remove promptly; do not bleach; tumble dry low
How to use
How to Choose Base Layers
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.
