Castelli call it the Pioggia shoe cover, and although the name is Italian for "rain," that doesn't really capture the essence of this bootie. Sure, it's completely waterproof, with sealed seams, a waterproof zipper and a silicone-sealed top edge to keep water from entering. Castelli have backed the PU-coated fabric with fleece to make this bootie warm in the coldest conditions, while the high stretch also gives it a close, comfortable and aero fit. Key Features:Waterproof fleece-lined bootie for cold and wet conditions,Waterproof PU-coated stretch fabric with fleece layer inside,Silicone bead at inside top of cuff to seal water out,Wrap cuff construction to optimize fit,Pull tab on inside for easy entry,High-durability material under foot,108g (Pair),Temperature Range: -2° - +12°C.