BOOT DUCKS, ski boot liners, Medium fit boots up to 26 cm/41 eu. If you use boot heaters, boot dryers or boot warmers get Boot Ducks. Keep feet dry all day. Also sold in Large up to 31 cm/47 eu boots Designed to be worn as a waterproof liner over your boot liners / inner boots Forms a waterproof barrier between your boot liners and your boot shells Prevents snow, ice particles, and water from soaking into your boot liners and your feet Made of special polymers that remain tough and flexible, even in sub-zero temperatures Effective for Men, Women, Teens, and Children. Keeps your feet dry and comfortable all day long !