The sealskinz windproof skull cap has been designed to be worn underneath your helmet giving you extra comfort and warmth the close fitting lightweight and breathable cap features a micro fleece lining to give you that extra warmth on those colder riding days the breathable fabric allows for any moisture to escape to ensure your head stays feeling dry and fresh being windproof and covering your head the sealskinz cap will keep you warm when the wind picks up lastly the sealskinz windproof