This reversible beanie has fleece on one side and a polymer blend on the other. Both sides incorporate Cocona fabric, which is made from mashed coconut shells and boasts excellent moisture-wicking and sun-protection properties. If the conditions are warm enough that your head's going to sweat, wear the poly blend on the inside to wick away the moisture. If the conditions are colder, or wetter, wear the fleece on the inside. The poly blend has enough water resistance to keep your hair dry in all but the wettest scenarios, and even when water does soak through the outer layer, the fleece provides enough insulation to keep your head warm.