Size is M and they are pretty much identical to the K2 superlight (check AMH), but without the nylon gaiter (i.e. there is a short collar above the top of the neoprene). So picture the overboot shown at the website, but with a much shorter collar. That's why they're so nice-- they work really well with regular gaiters and there isn't the need to carry full overboots and full gaiters.