The Mens Terramar Microthermal Crew is a medium weight baselayer for reliable warmth. Made from 100% Polyester, the soft Microthermal Crew is lightweight with air pocket construction to trap warm air. This Terramar Body-Sensor shirt features a soft brushed filament inner layer to pull moisture away from skin and quickly transfer it to the outer layer for evaporation. Breathable Ec2 Qwik-Dri Thermoregulation Comfort Technology regulates temperature for quick-drying comfort. A UPF rating of 25+ protects you against harmful rays and the anti-microbial properties help keep stink at bay. The Mens Terramar Microthermal Crew is an ideal medium weight base layer for all cold weather activities.