You don't have to take it off and put it back on all day. It adapts to the ambient temperature – it warms up when it's cold and dissipates excess heat as it gets warmer. UA Storm Technology – Repels water without compromising breathability. Durable woven fabric on chest and collar – With lightweight fleece insulation for warmth without bulk. Smooth knit in body and sleeves - Provides breathability where you need it most. 1/2 Front Zip - Allows for easy dressing and comfortable layering. Built-in T-shirt holder – Located virtually on the user's right side.