The winter cap is the secret weapon of European based pros. Also known as the mutt, these caps drop cotton construction in favor of man made fibers to provide insulation and wick moisture away from your head. They also add a knitted earflap to keep your ears warm in biting wind. The Castelli Risvolto Winter Cap is one of those hard to find Euro style mutts. Constructed from polyester, the cap uses a polypropylene liner to improve insulation and wick moisture. The earflap folds up and out of the way in case the day warms noticeably. While some mutts are too bulky to wear under a helmet, the Risvolto Winter Cap will fit beneath your helmet with just a slight loosening of your helmet's chin strap and occipital retention device. The Castelli Risvolto Winter Cap comes in Blackred, Blackwhite, and Redwhite and one size fits all.