Unless you are buying for an upper elementary school/middle school child, stick wit the M/L size. I dont normally have any knee problems, Im in my late 20s, so I was surprised to have so much pain the next day that I had to take some ibuprofen to be able to walk. Contoured nicely with good support, they are roomier in the strap nearest to my leg, but do not feel too big or slip when I walk. I have worn the same pair every day for 3 months AND I wont leave home without them. Fue un regalo para mi madre y quedó muy satisfecha. WTF was this company thinking. The headset comes with two different options for wearing it. he Will Not wear just “ANYTHING” . It sinches well, is strong and if you are strong as well can be laced without help. Love the cork storage - this is a great way to save them for crafts.