Base Layer and Underwear

ACTIVE SPORT ankle-length base layer bottom. Elastic waistband. Men ACTIVE style.

These heavyweight RedHEAT EXTREME men's base layer ankle-length bottoms live up to their name with optimal body temperature regulation. The innovative technical fabric of these thermal long johns stores and manages body heat through carbon microcrystals f

This lightweight RedHEAT ACTIVE men's base layer crew neck top lives up to its name with optimal body temperature regulation. The innovative technical fabric of our men’s thermal base layer incorporates carbon microcrystals that store body heat, while its

This lightweight RedHEAT ACTIVE men's base layer zip top lives up to its name with optimal body temperature regulation. The innovative technical fabric of our men’s thermal base layer incorporates carbon microcrystals that store body heat, while its micro

This heavyweight RedHEAT EXTREME men's base layer zip top lives up to its name with optimal body temperature regulation. The innovative technical fabric stores and manages body heat through carbon microcrystals for maximum comfort, making it the perfect t

Smartwool Men's Classic Thermal Merino Base Layer 1/4 Zip Boxed Charcoal Heather

Smartwool Men's Classic Thermal Merino Base Layer Colorblock Crew Boxed Deep Navy/Laguna Blue

Smartwool Men's Classic Thermal Merino Base Layer Pattern Crew Boxed Black Mountain Scape

Smartwool Men's Classic Thermal Merino Base Layer Crew Boxed Laguna Blue Heather

Our best-selling base layer bottoms made from soft and breathable 100% merino wool jersey, the 200 Oasis Leggings are the perfect foundation for your cold-weather layering.

The targeted insulation and ventilation in the Men’s Merino 250 Base Layer Bottoms allow you to stay comfortable while you’re out working up a sweat.

This heavyweight RedHEAT EXTREME men's base layer bottoms are ideal for skiing. Living up to their name with optimal body temperature regulation, the innovative technical fabric of these 3/4-length thermal underwear stores and manages body heat through ca