Size Small for ages 0-9 months. Wear over bare feet, socks, slippers or shoes, throughout fall, winter and spring! The Booties go on easily, stay on with two adjustable toggles, and keep wind and cold out. Comprised of a water and wind-resistant 600D nylon upper, inner fleece lining and skid-resistant Toughtek® soles for all types of outdoor play. For colder weather, layer up with a pair of our Sherpa-fleece Linerz.