Our Skull Cap/ Helmet Liner is tapered to cover your ears and forehead, and contoured at the nape of your neck to hug your head. Professionally bound  at the hem with supplex lycra which provides a snug fit to keep the elements out. We selected a 4-way stretch fabric, so the fit is universal. Polartec Wind Pro® is a fantastic fabric engineered for performance in cold conditions. We chose a hard-faced (meaning smooth on the outside) fabric with fleece on the inside for use under all types of helmets. It is thin enough to not affect your helmet’s fit and it still is waterproof, wind resistant, provides insulation and is abrasion resistant. All these great characteristics and it is still breathable and machine washable! And for the icing on the cake: it is made in the USA (the product and the fabric!) Our style choice has a subtle grid pattern reminiscent of carbon fiber weaves! What’s not to love?! In addition to using this skull cap on chilly bike rides, we also keep these in our car in case of an emergency in bad weather; they take up no storage room!