Im 411 and 102 lbs and bought the small. The Rival 310 was the way more comfortable, but it was slightly large and heavy for me. I was able to buy some old glass lenses for about $30 (28mm, 50mm) and take some outstanding portraits and landscapes. These are great headphones folks, Ive been using them about a month. I purchased these for bridesmaids gifts. But either way, the slides are great and I couldn’t be happier. Shipping was very fast. If someone could show me 1. But once they arrived they fit. It is embarrassing because it makes my foot look dirty.