Men's Base Layer Tops
(81 products)- CraftCORE Dry Active Comfort Base Layer Top - Men's$39.73Save 38%compared to $64.95Members use code OUT4JUL25 for $20 off $100+ at REI OutletUnderwear Weight:MidweightSize Type:Regular, BigREI OUTLET
- IcebreakerMerino 260 Tech Long-Sleeve Half-Zip Thermal Base Layer Top - Men'sTop Rated$99.73Save 26%compared to $135.00Members use code OUT4JUL25 for $20 off $100+ at REI OutletUnderwear Weight:HeavyweightSize Type:Regular, BigREI OUTLET
- SaxxRoast Master Midweight Long-Sleeve Crew Base Layer Top - Men's$52.73Save 29%compared to $75.00Members use code OUT4JUL25 for $20 off $100+ at REI OutletUnderwear Weight:MidweightSize Type:Regular, BigREI OUTLET
- Free CountryMicrotech Heat Cocaber Base Layer Top - Men's$21.73Save 45%compared to $40.00Members use code OUT4JUL25 for $20 off $100+ at REI OutletUnderwear Weight:LightweightSize Type:BigREI OUTLET
- Arms of Andes160 Ultralight Alpaca Wool Crewneck Base Layer T-Shirt - Men's$75.00Underwear Weight:UltralightweightSize Type:Regular, Big
- PatagoniaCapilene Thermal Weight Zip-Neck Top - Men's$109.00Underwear Weight:HeavyweightSize Type:Regular
- IcebreakerMerino 260 Tech Long-Sleeve Crewe Thermal Top - Men'sTop Rated$125.00Underwear Weight:HeavyweightSize Type:Regular, Big
- IcebreakerMerino 260 Tech Long Sleeve Crewe Base Layer Top - Men'sTop Rated$119.73Save 27%compared to $165.00Members use code OUT4JUL25 for $20 off $100+ at REI OutletUnderwear Weight:HeavyweightSize Type:Regular, BigREI OUTLET
- Icebreaker200 Oasis Crewe Base Layer Top - Men'sTop Rated$95.00Underwear Weight:MidweightSize Type:Regular, Big
- Arms of Andes160 Ultralight Alpaca Wool Long-Sleeve Base Layer Shirt - Men's$85.00Underwear Weight:UltralightweightSize Type:Regular, Big
- SmartwoolIntraknit Thermal Merino Crew Base Layer Top - Men's$92.73Save 28%compared to $130.00Members use code OUT4JUL25 for $20 off $100+ at REI OutletUnderwear Weight:MidweightSize Type:Regular, BigREI OUTLET
- REI Co-opMerino 185 Long-Sleeve Base Layer Top - Men's Tall SizesTop Rated$79.95Underwear Weight:LightweightSize Type:Tall, Big
- Picture Organic ClothingNangha Base Layer Top - Men's$44.83Save 50%compared to $90.00Underwear Weight:MidweightSize Type:Regular, Big
- PatagoniaCapilene Thermal Weight Long Underwear Crew Top - Men's$99.00Underwear Weight:HeavyweightSize Type:Regular
- Icebreaker200 Oasis Long-Sleeve Half-Zip Base Layer Top - Men'sTop Rated$115.00Underwear Weight:MidweightSize Type:Regular, Big
- Icebreaker150 Anatomica Crewe Base Layer Top - Men's$75.00Underwear Weight:LightweightSize Type:Regular, Big
- IcebreakerMerino 260 Tech Long-Sleeve Half-Zip Base Layer Top - Men'sTop Rated$135.00Underwear Weight:MidweightSize Type:Regular, Big
- REI Co-opMerino 185 Long-Sleeve Half-Zip Base Layer Top - Men's Tall SizesTop Rated$89.95Underwear Weight:LightweightSize Type:Tall, Big
- IcebreakerMerino 125 ZoneKnit Long-Sleeve Half-Zip Base Layer Top - Men'sTop Rated$99.73Save 26%compared to $135.00Members use code OUT4JUL25 for $20 off $100+ at REI OutletUnderwear Weight:LightweightSize Type:Regular, BigREI OUTLET
- SmartwoolIntraknit Thermal Merino Crew Base Layer Top - Men's$130.00Underwear Weight:MidweightSize Type:Regular, Big
- SmartwoolIntraknit Thermal Merino Base Layer Colorblock Crew - Men's$96.73Save 25%compared to $130.00Members use code OUT4JUL25 for $20 off $100+ at REI OutletUnderwear Weight:MidweightSize Type:Regular, BigREI OUTLET
- Free CountryForce Grid Fleece Crew Base Layer Top - Men'sTop Rated$26.73Save 40%compared to $45.00Members use code OUT4JUL25 for $20 off $100+ at REI OutletUnderwear Weight:LightweightSize Type:BigREI OUTLET
- Icebreaker125 ZoneKnit Crewe Base Layer Shirt - Men's$84.73Save 26%compared to $115.00Members use code OUT4JUL25 for $20 off $100+ at REI OutletUnderwear Weight:LightweightSize Type:Regular, BigREI OUTLET
- SmartwoolIntraknit Thermal Merino Pattern Crew Base Layer Top - Men's$75.73Save 41%compared to $130.00Members use code OUT4JUL25 for $20 off $100+ at REI OutletUnderwear Weight:LightweightSize Type:BigREI OUTLET
- CotopaxiLiso Base Layer Top - Men'sTop Rated$44.73Save 31%compared to $65.00Members use code OUT4JUL25 for $20 off $100+ at REI OutletUnderwear Weight:MidweightSize Type:BigREI OUTLET
- SmartwoolIntraknit Active Base Layer Crew Shirt - Men's$81.73Save 25%compared to $110.00Members use code OUT4JUL25 for $20 off $100+ at REI OutletUnderwear Weight:MidweightSize Type:Regular, BigREI OUTLET
- ArtilectDarkhorse 185 Zoned Crew Base Layer Top - Men'sTop Rated$109.73Save 31%compared to $160.00Members use code OUT4JUL25 for $20 off $100+ at REI OutletUnderwear Weight:MidweightSize Type:Regular, BigREI OUTLET
- Arc'teryxRho Heavyweight Zip-Neck Base Layer Top - Men's$112.73Save 19%compared to $140.00Members use code OUT4JUL25 for $20 off $100+ at REI OutletUnderwear Weight:HeavyweightSize Type:BigREI OUTLET
- Free CountryForce Grid Fleece Base Layer Top - Men's$29.73Save 33%compared to $45.00Members use code OUT4JUL25 for $20 off $100+ at REI OutletUnderwear Weight:LightweightSize Type:BigREI OUTLET
- Helly HansenLifa Merino Midweight Half-Zip Base Layer Top - Men's$110.00Underwear Weight:MidweightSize Type:Regular