THERMAL UNDERWEAR SET The best way to keep warm is to wear several layers. The Thermal Underwear Set is developed to be worn close to your skin. The ComfoTech undershirt and leggings transport body moisture away from the body. The undershirt is long-sleeved and has a polo neck with zip. The pants are specially designed for riders and feature long legs with foot straps, an extra gusset and no inner seams. Black Only. Unisex Sizing.