Defend is for the not-too-hot, not-too-cold, just right for the right-now adventurers - pure, and functional. Designed with Polartec® fabric to keep your head warm on the coldest days on the bike. Polartec® fabric actively regulates heat to keep you warm and dry. Designed to stay up during rough downhill and out of the way when you need to breathe hard during a climb. One size fits most.