With the warmth of Terraprene and the comfort of our ThermalPlush lining, this Short Sleeve Hydroskin Shirt works to keep you warm in all seasons. Wear it alone in the warmer months when the H2O is still chilly, and wear it as part of a layering system as the air temperature drops.0.5-mm Terraprene core insulates and Safe guards.4-way stretch PowerSpan outer layer allows easy, unrestricted mobility. New ThermalPlush lining increases insulation, repels moisture, and dries quickly. Titanium laminate adhesive aids in body heat retention. Lycra underarms eliminate binding, making this top superior both as a single, outer layer or as a base layer. DWR coating forces H2O to bead and roll off for decreased evaporative cooling and quicker drying times between trips.