Giro Peloton Cap
The Peloton Cap might be the most versatile accessory a rider can have on a warm day. It provides a bit of shade from the sun, a layer of insulation when it's cool or windy, and it wicks sweat when the heat rises, too. Designed to be worn under a helmet, it is thin enough to fit without bunching and light enough to practically disappear when you put it on. The brim has also been shortened (compared to some caps), for better upper peripheral vision when riding in the drops.