One layer that you don't have to take off and put on all day long. It adapts to the ambient temperature – it warms up when it's cold and dissipates excess heat when it gets warmer.UA Storm Technology – Repels water without compromising breathability.Durable woven material on chest and collar – With lightweight fleece insulation for warmth without unnecessary bulk.Smooth and breathable knit on body and sleeves – Provides breathability where you need it most.Secure zippered pockets – Allow you to store small items or keep your hands warm.Built-in T-shirt holder – Located practically on the right side of the user.