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Long Sleeve Underwear

(201 products)

Products (201)

Sort: Best Match

SmartwoolIntraknit Thermal Merino Crew Base Layer Top - Women's
$130.00
189 reviews with an average rating of 4.3 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular
SmartwoolIntraknit Thermal Merino Crew Base Layer Top - Men's
$92.73
Save 28%
compared to $130.00
Members use code OUT4JUL25 for $20 off $100+ at REI Outlet
9 reviews with an average rating of 4.1 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
REI OUTLET
Arms of Andes300 Lightweight Alpaca Wool Half-Zip Base Layer Top - Men's
$135.00
14 reviews with an average rating of 3.9 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular, Big
SmartwoolIntraknit Thermal Merino Pattern Crew Base Layer Top - Men's
$75.73
Save 41%
compared to $130.00
Members use code OUT4JUL25 for $20 off $100+ at REI Outlet
2 reviews with an average rating of 4.5 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Big
REI OUTLET
Kari TraaEmbla Wool Long-Sleeve Base Layer Top - Women's
$80.00
0 reviews
Underwear Weight:
Ultralightweight
Size Type:
Regular
SmartwoolIntraknit Active Base Layer Crew Shirt - Men's
$81.73
Save 25%
compared to $110.00
Members use code OUT4JUL25 for $20 off $100+ at REI Outlet
1 reviews with an average rating of 4.0 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
REI OUTLET
Arms of Andes300 Alpaca Wool Long-Sleeve Crew Base Layer Top - Men's
$130.00
7 reviews with an average rating of 3.6 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular, Big
Top Rated
Free CountryForce Grid Fleece Crew Base Layer Top - Men's
$26.73
Save 40%
compared to $45.00
Members use code OUT4JUL25 for $20 off $100+ at REI Outlet
5 reviews with an average rating of 5.0 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Big
REI OUTLET
Icebreaker125 ZoneKnit Long-Sleeve Crewe Base Layer Top - Men's
$125.00
4 reviews with an average rating of 5.0 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular, Big
SmartwoolIntraknit Thermal Max Merino Quarter-Zip Base Layer Top - Men's
$155.00
0 reviews
Underwear Weight:
Midweight
Size Type:
Regular, Big
Free CountryMicrotech Heat Cocaber Base Layer Top - Men's
$21.73
Save 45%
compared to $40.00
Members use code OUT4JUL25 for $20 off $100+ at REI Outlet
2 reviews with an average rating of 5.0 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Big
REI OUTLET
Arms of Andes300 Lightweight Alpaca Wool Half-Zip Base Layer Top - Women's
$115.00 - $135.00
8 reviews with an average rating of 3.8 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular
Top Rated
Icebreaker200 Oasis Long-Sleeve Half-Zip Base Layer Top - Women's
$115.00
18 reviews with an average rating of 4.9 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular
CraftCORE Dry Active Comfort Base Layer Top - Women's
$39.73
Save 38%
compared to $64.95
Members use code OUT4JUL25 for $20 off $100+ at REI Outlet
3 reviews with an average rating of 3.7 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular
REI OUTLET
Terramar2.0 Cloud Nine Midweight Performance Base Layer Scoop Shirt - Women's
$29.73
Save 33%
compared to $45.00
Members use code OUT4JUL25 for $20 off $100+ at REI Outlet
1 reviews with an average rating of 5.0 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular
REI OUTLET
Top Rated
Icebreaker200 Oasis Long-Sleeve Half-Zip Base Layer Top - Men's
$115.00
17 reviews with an average rating of 4.8 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
Free CountryForce Grid Fleece Base Layer Top - Men's
$29.73
Save 33%
compared to $45.00
Members use code OUT4JUL25 for $20 off $100+ at REI Outlet
4 reviews with an average rating of 4.5 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Big
REI OUTLET
Kari TraaLucie Half-Zip Base Layer Top - Women's
$67.73
Save 24%
compared to $90.00
Members use code OUT4JUL25 for $20 off $100+ at REI Outlet
0 reviews
Underwear Weight:
Lightweight
Size Type:
Regular
REI OUTLET
IcebreakerMerino 260 Vertex Long-Sleeve Crewe Natural Shades Base Layer Top - Women's
$104.73
Save 25%
compared to $140.00
Members use code OUT4JUL25 for $20 off $100+ at REI Outlet
2 reviews with an average rating of 5.0 out of 5 stars
Underwear Weight:
Heavyweight
Size Type:
Regular
REI OUTLET
Picture Organic ClothingNangha Base Layer Top - Men's
$44.83
Save 50%
compared to $90.00
0 reviews
Underwear Weight:
Midweight
Size Type:
Regular, Big
Arms of Andes300 Lightweight Alpaca Wool Pullover Base Layer Hoodie - Women's
$140.00
1 reviews with an average rating of 5.0 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular
Kari TraaAlma Half-Zip Base Layer Top - Women's
$59.73
Save 25%
compared to $80.00
Members use code OUT4JUL25 for $20 off $100+ at REI Outlet
0 reviews
Underwear Weight:
Ultralightweight
Size Type:
Regular
REI OUTLET
Ortovox185 Merino Rock'n'wool Long-Sleeve Base Layer Top - Men's
$110.00
10 reviews with an average rating of 4.2 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
Kari TraaRose Base Layer Hoodie - Women's
$97.73
Save 24%
compared to $130.00
Members use code OUT4JUL25 for $20 off $100+ at REI Outlet
1 reviews with an average rating of 5.0 out of 5 stars
Underwear Weight:
Heavyweight
Size Type:
Regular
REI OUTLET
Top Rated
IcebreakerMerino 260 Tech Long-Sleeve Half-Zip Base Layer Top - Men's
$135.00
34 reviews with an average rating of 4.5 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
Top Rated
The North FaceSummit Series Pro 120 Crew Base Layer Top - Women's
$100.00
12 reviews with an average rating of 5.0 out of 5 stars
Underwear Weight:
Ultralightweight
Size Type:
Regular, Plus
Arms of Andes160 Ultralight Alpaca Wool Long-Sleeve Base Layer Shirt - Women's
$85.00 - $100.00
11 reviews with an average rating of 3.8 out of 5 stars
Underwear Weight:
Ultralightweight
Size Type:
Regular
PatagoniaCapilene Thermal Weight Zip-Neck Long Underwear Top - Women's
$109.00
14 reviews with an average rating of 4.1 out of 5 stars
Underwear Weight:
Heavyweight
Size Type:
Regular
Free CountryForce Grid Fleece Base Layer Top - Women's
$34.73
Save 36%
compared to $55.00
Members use code OUT4JUL25 for $20 off $100+ at REI Outlet
1 reviews with an average rating of 5.0 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular
REI OUTLET
Free CountryMicrotech Heat Base Layer Top - Men's
$28.73
Save 36%
compared to $45.00
Members use code OUT4JUL25 for $20 off $100+ at REI Outlet
0 reviews
Underwear Weight:
Lightweight
Size Type:
Big
REI OUTLET

91–120 of 201 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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