Grinding up your local hill o' death is hard enough when you can see where you're going, but when you find yourself blinded by sweat, it's time for the Castelli Summer Skullcap. Carefully constructed to sit smoothly under your helmet, the Skullcap combines a sweat-absorbing headband with a cooling and wicking mesh top to keep your focus on the ride, not on the sweat that's stinging your corneas.