On or off the bike, the Giro Merino Wool Cap is a cyclist's staple. The wool cap insulates to keep your head warm, but the X-Static liner breathes well and wicks moisture away from your skin. It's substantial enough to wear alone off the bike, and thin enough to wear under your helmet for a little extra warmth. Merino also fights odor, so it won't stink, even after sweaty rides. Giro also added ear flaps that fold up or down for added protection and a short, reinforced brim to keep rain and sun out of your eyes.