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Long Sleeve Base Layers

(234 products)

Products (234)

Sort: Best Match

SmartwoolClassic All-Season Merino Quarter-Zip Base Layer Top - Men's
$46.83 - $95.00
4 reviews with an average rating of 4.8 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
REI Co-opMerino 185 Long-Sleeve Base Layer Top - Women's Plus Sizes
$79.95
29 reviews with an average rating of 4.4 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Plus
Top Rated
SmartwoolClassic Thermal Merino Crew Base Layer Top - Men's
$85.73
Save 25%
compared to $115.00
Members use code LABORDAY2025 for an extra 20% off at REI Outlet
276 reviews with an average rating of 4.7 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular
REI OUTLET
PatagoniaCapilene Thermal Weight Zip-Neck Top - Men's
$69.93 - $109.00
18 reviews with an average rating of 4.0 out of 5 stars
Underwear Weight:
Heavyweight
Size Type:
Regular, Big
Top Rated
PatagoniaCapilene Midweight Zip-Neck Base Layer Top - Men's
$69.93 - $99.00
61 reviews with an average rating of 4.6 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
Top Rated
SmartwoolClassic Thermal Merino Base Layer Quarter-Zip - Men's
$89.73
Save 25%
compared to $120.00
Members use code LABORDAY2025 for an extra 20% off at REI Outlet
20 reviews with an average rating of 4.7 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular
REI OUTLET
Top Rated
SmartwoolClassic All Season Merino Long-Sleeve Base Layer Top - Men's
$66.73
Save 25%
compared to $90.00
Members use code LABORDAY2025 for an extra 20% off at REI Outlet
66 reviews with an average rating of 4.5 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular
REI OUTLET
Top Rated
REI Co-opHeavyweight Merino Long-Sleeve Base Layer Crew Top - Women's
$99.95
25 reviews with an average rating of 4.6 out of 5 stars
Underwear Weight:
Heavyweight
Size Type:
Regular, Plus
Top Rated
REI Co-opMerino Midweight Base Layer Crew Top - Kids'
$49.95
25 reviews with an average rating of 4.7 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular
Top Rated
SmartwoolClassic Thermal Merino Quarter-Zip Base Layer Top - Men's
$120.00
20 reviews with an average rating of 4.7 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
REI Co-opHeavyweight Merino Long-Sleeve Base Layer Crew Top - Men's
$99.95
23 reviews with an average rating of 4.4 out of 5 stars
Underwear Weight:
Heavyweight
Size Type:
Regular, Big, Tall
Top Rated
Arc'teryxRho Merino Wool Crew Neck Base Layer Top - Men's
$120.00
27 reviews with an average rating of 4.8 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
tasc PerformanceElevation Merino T-Shirt - Women's
$49.73
Save 37%
compared to $79.00
Members use code LABORDAY2025 for an extra 20% off at REI Outlet
77 reviews with an average rating of 4.5 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular, Plus
REI OUTLET
REI Co-opMerino 185 Long-Sleeve Half-Zip Base Layer Top - Women's Plus Sizes
$29.83 - $89.95
18 reviews with an average rating of 4.3 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Plus
REI Co-opHeavyweight Merino Base Layer Half-Zip Top - Men's
$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
Arc'teryxRho LT Crew Neck Base Layer Top - Men's
$70.93 - $100.00
28 reviews with an average rating of 4.8 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular, Big
Top Rated
REI Co-opHeavyweight Merino Base Layer Half-Zip Top - Women's
$104.95
20 reviews with an average rating of 4.6 out of 5 stars
Underwear Weight:
Heavyweight
Size Type:
Regular, Plus
CraftCORE Dry Active Comfort Base Layer Top - Men's
$39.73
Save 38%
compared to $64.95
Members use code LABORDAY2025 for an extra 20% off at REI Outlet
0 reviews
Underwear Weight:
Midweight
Size Type:
Regular, Big
REI OUTLET
SmartwoolIntraknit Active Base Layer Crew Shirt - Men's
$74.73
Save 32%
compared to $110.00
Members use code LABORDAY2025 for an extra 20% off at REI Outlet
1 reviews with an average rating of 4.0 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Big, Regular
REI OUTLET
SmartwoolIntraknit Thermal Merino Crew Base Layer Top - Men's
$130.00
188 reviews with an average rating of 4.4 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
Ortovox230 Competition Zip-Neck Base Layer Top - Men's
$59.83
Save 50%
compared to $120.00
3 reviews with an average rating of 3.7 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
IcebreakerMerino 260 Tech Long-Sleeve Half-Zip Thermal Base Layer Top - Men's
$99.73
Save 26%
compared to $135.00
Members use code LABORDAY2025 for an extra 20% off at REI Outlet
37 reviews with an average rating of 4.4 out of 5 stars
Underwear Weight:
Heavyweight
Size Type:
Regular, Big
REI OUTLET
KUHLReactiv Lite Grid Quarter-Zip Base Layer Top - Men's
$119.00
1 reviews with an average rating of 5.0 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular, Big
Top Rated
Helly HansenLIFA Merino Midweight Half-Zip Base Layer Top - Men's
$79.73
Save 27%
compared to $110.00
Members use code LABORDAY2025 for an extra 20% off at REI Outlet
5 reviews with an average rating of 4.8 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
REI OUTLET
Top Rated
IcebreakerMerino 200 Oasis Long-Sleeve Crewe Thermal Top - Men's
$78.73
Save 25%
compared to $105.00
Members use code LABORDAY2025 for an extra 20% off at REI Outlet
64 reviews with an average rating of 4.5 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Big, Regular
REI OUTLET
New arrival
Outdoor ResearchAlpine Onset Merino 150 Base Layer Hoodie - Men's
$119.00
2 reviews with an average rating of 5.0 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular, Big
PatagoniaCapilene Thermal Weight Long Underwear Crew Top - Men's
$99.00
10 reviews with an average rating of 4.3 out of 5 stars
Underwear Weight:
Heavyweight
Size Type:
Regular, Big
Top Rated
IcebreakerMerino 260 Tech Long-Sleeve Crewe Thermal Top - Men's
$125.00
58 reviews with an average rating of 4.7 out of 5 stars
Underwear Weight:
Heavyweight
Size Type:
Regular, Big
Top Rated
SmartwoolIntraknit Thermal Merino Base Layer Quarter-Zip Top - Men's
$140.00
11 reviews with an average rating of 4.9 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
IcebreakerMerino 260 Tech Long-Sleeve Half-Zip Base Layer Top - Men's
$135.00
37 reviews with an average rating of 4.4 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big

31–60 of 234 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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