My 22 year-old is always cold. After he wore through a pair of Christmas socks (I don't think these are meant to last longer than the photo or the tree), I decided he needed something cozier and more durable. He's a half-size, and I bought the 9 and the 10, intending to return one of the pairs, and the Uggs fleece jacket.. The 9's worked, and this kid is finally warm. It's been 6 days and he hasn't taken either the slippers or the jacket off. And his younger brother - who runs hot and lives barefooted - is lowkey jealous. He ended up nabbing the larger pair of slippers.