Our lightest base layer with the added boost of HeiQ tech in a slim fit. Light, versatile, and casual, the men's Lightweight Base Layer Crewneck does all the stuff a good base layer should do with a look and feel that is comfortable on and off the mountain. HeiQ tech boosts temperature regulation and odor resistance to keep you comfortable longer. Features: A slim fit with four-way stretch makes for easy layering and an unrestricted feel. HeiQ Smart Temp tech regulates body temperature to keep you cool through changing temps and extended efforts. HeiQ Fresh tech manages odor and the perma-stink associated with synthetic knits to keep you feeling and smelling fresh. Product meets Bluesign® approved safety and environmental standards in manufacturing.