This collection of Hot Chillys men's base layers offers lightweight, midweight and mountain weight base layer and accessories for all of life's outdoor pursuits. Our products are available in a body fit athletic design with 4-way stretch for a full range of movement, or relaxed fit that lies gently on the skin without binding. Engineered with performance in mind, our men's thermal long underwear will keep you dry, warm and very comfortable so you can concentrate on having a good time. We aren't out to change the world, we just want to change your underwear. Browse our selection of men's thermal long johns today.