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Long Sleeve Underwear

(202 products)

Products (202)

Sort: Best Match

Top Rated
Arc'teryxRho Base Layer Hoody - Women's
$96.73
Save 19%
compared to $120.00
Members use code OUT4JUL25 for $20 off $100+ at REI Outlet
21 reviews with an average rating of 4.9 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular
REI OUTLET
Top Rated
PatagoniaCapilene Midweight Crew Base Layer Top - Women's
$89.00
45 reviews with an average rating of 4.6 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Plus
Top Rated
REI Co-opLightweight Base Layer Crew Top - Kids'
$29.95
12 reviews with an average rating of 4.8 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular
REI Co-opHeavyweight Merino Long-Sleeve Base Layer Crew Top - Men's
$49.83 - $99.95
22 reviews with an average rating of 4.4 out of 5 stars
Underwear Weight:
Heavyweight
Size Type:
Regular, Big, Tall
Top Rated
PatagoniaCapilene Midweight Crew Base Layer Top - Men's
$89.00
79 reviews with an average rating of 4.5 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
SmartwoolClassic Thermal Merino Base Layer Quarter-Zip - Women's
$89.73
Save 25%
compared to $120.00
Members use code OUT4JUL25 for $20 off $100+ at REI Outlet
0 reviews
Underwear Weight:
Midweight
Size Type:
Regular, Plus
REI OUTLET
Top Rated
REI Co-opMidweight Crew Base Layer Top - Toddlers'
$24.95
14 reviews with an average rating of 4.7 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular
PatagoniaCapilene Midweight Crew Base Layer Top - Kids'
$26.93
Save 30%
compared to $39.00
1 reviews with an average rating of 5.0 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular
Top Rated
REI Co-opHeavyweight Merino Base Layer Half-Zip Top - Women's
$29.83 - $104.95
19 reviews with an average rating of 4.7 out of 5 stars
Underwear Weight:
Heavyweight
Size Type:
Regular, Plus
Kari TraaFryd Base Layer Top - Women's
$19.83 - $60.00
21 reviews with an average rating of 4.0 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular
SmartwoolClassic Thermal Merino Crew Base Layer Top - Kids'
$44.73
Save 31%
compared to $65.00
Members use code OUT4JUL25 for $20 off $100+ at REI Outlet
5 reviews with an average rating of 3.6 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular
REI OUTLET
REI Co-opMerino 185 Long-Sleeve Half-Zip Base Layer Top - Women's Plus Sizes
$62.93 - $89.95
18 reviews with an average rating of 4.3 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Plus
Top Rated
IcebreakerMerino 200 Oasis Long-Sleeve Crewe Thermal Top - Women's
$105.00
129 reviews with an average rating of 4.7 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Plus
REI Co-opHeavyweight Merino Base Layer Half-Zip Top - Men's
$49.83 - $104.95
15 reviews with an average rating of 3.9 out of 5 stars
Underwear Weight:
Heavyweight
Size Type:
Regular, Big, Tall
Top Rated
SmartwoolClassic All Season Merino Long-Sleeve Base Layer Top - Men's
$66.73
Save 25%
compared to $90.00
Members use code OUT4JUL25 for $20 off $100+ at REI Outlet
64 reviews with an average rating of 4.6 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular
REI OUTLET
Top Rated
SmartwoolClassic Thermal Merino Quarter-Zip Base Layer Top - Men's
$120.00
18 reviews with an average rating of 4.6 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
Kari TraaMina Long-Sleeve Base Layer Top - Women's
$44.73
Save 25%
compared to $60.00
Members use code OUT4JUL25 for $20 off $100+ at REI Outlet
2 reviews with an average rating of 2.5 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular
REI OUTLET
Top Rated
IcebreakerMerino 200 Oasis Long-Sleeve Half-Zip Thermal Base Layer Top - Women's
$84.73
Save 26%
compared to $115.00
Members use code OUT4JUL25 for $20 off $100+ at REI Outlet
18 reviews with an average rating of 4.9 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Plus
REI OUTLET
Top Rated
Arc'teryxIonia Merino Wool Base Layer Hoody - Men's
$140.00
49 reviews with an average rating of 4.9 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
SmartwoolIntraknit Thermal Merino Crew Base Layer Top - Women's
$96.73
Save 25%
compared to $130.00
Members use code OUT4JUL25 for $20 off $100+ at REI Outlet
120 reviews with an average rating of 4.3 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular
REI OUTLET
Top Rated
SmartwoolClassic Thermal Merino Crew Base Layer Top - Men's
$85.73
Save 25%
compared to $115.00
Members use code OUT4JUL25 for $20 off $100+ at REI Outlet
276 reviews with an average rating of 4.7 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular
REI OUTLET
Top Rated
Arc'teryxRho Zip-Neck Base Layer Top - Women's
$120.00
36 reviews with an average rating of 4.8 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular, Plus
Top Rated
REI Co-opLightweight Crew Base Layer Top - Infants'/Toddlers'
$19.95
10 reviews with an average rating of 5.0 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular
Top Rated
IcebreakerMerino 200 Oasis Long-Sleeve Crewe Thermal Top - Men's
$105.00
132 reviews with an average rating of 4.7 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
Top Rated
Icebreaker260 Tech Long-Sleeve Crewe Base Layer Top - Women's
$125.00
36 reviews with an average rating of 4.7 out of 5 stars
Underwear Weight:
Heavyweight
Size Type:
Regular, Plus
SmartwoolClassic Thermal Merino Lettuce Edge Crew Base Layer Top - Women's
$82.73
Save 28%
compared to $115.00
Members use code OUT4JUL25 for $20 off $100+ at REI Outlet
0 reviews
Underwear Weight:
Midweight
Size Type:
Regular
REI OUTLET
Top Rated
IcebreakerMerino 200 Oasis Long-Sleeve Base Layer Crew Top - Kids'
$41.93 - $60.00
8 reviews with an average rating of 4.5 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular
Top Rated
IcebreakerMerino 260 Tech Long-Sleeve Half-Zip Thermal Base Layer Top - Women's
$99.73
Save 26%
compared to $135.00
Members use code OUT4JUL25 for $20 off $100+ at REI Outlet
25 reviews with an average rating of 4.6 out of 5 stars
Underwear Weight:
Heavyweight
Size Type:
Regular, Plus
REI OUTLET
Top Rated
Arc'teryxRho Hoody Base Layer Top - Women's
$104.93
Save 19%
compared to $130.00
37 reviews with an average rating of 4.6 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular
REI Co-opMerino 185 Long-Sleeve Base Layer Top - Women's Plus Sizes
$55.93 - $79.95
28 reviews with an average rating of 4.4 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Plus

31–60 of 202 products

Sort: Best Match

Related Expert Advice articles

What material is best?

Wool is moisture-wicking and odor-resistant, while synthetic fabrics are more durable and less expensive.

Match the temp to the trek

Lightweight layers are best for moderate to cool temperatures. Midweight layers are best for cold temperatures. Heavyweight layers are best for below-freezing temperatures.

Find your fit

To be able to wick sweat efficiently, your next-to-skin layer needs to actually be next to your skin. A comfortably snug fit everywhere is your goal.

Read full article: How to Choose Base Layers

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