The Skull hat weighs basically nothing, and the Windstopper panel protects the front of your noggin from the slipstream, preventing the dreaded brain freeze. Flat seams mean no chafing, and the close fit wicks well and fits easily under a helmet.
The Skull is a nice piece, but beware that it fits small. A normal size head will probably take a large, and even then it's definitely a beanie, i.e. no ear protection. We'd love to see a version with ear flaps, but if you're looking for a minimalist skull cap give the Skull a try.