BBB underwear CoolLayer short-sleeves.Coolskin is an ultra-light, breathable polypropylene fiber, specifically developed and designed to keep you cool and dry in hot weather.The open mesh structure promotes air circulation between fabric and skin, while the pressure/pull effect absorbs perspiration from your skin to the outer fabric.Flat seams for added comfort.CoolLayer Cuissard.This jersey is perfect for the cyclist who trains all year round.It will keep you warm in cold weather and cool in hot.