Using this He - Man and the Masters Of The Universe 12 Days Of Socks Advent Calendar is easy. On December 1st, start opening one door each day. Inside, you'll find a new pair of socks. Make sure to keep track of the days so you don't miss any. When you get your new socks, simply put them on to keep your feet warm. As for maintenance, you can machine - wash these cotton socks on a gentle cycle. Just use a mild detergent and avoid using bleach. After washing, let them air - dry. These socks are for adults, so make sure the size (UK 6 - 10, EU 39 - 45, US 7 - 11) fits you or the person you're gifting them to.