Bought them for my sons 31+1 Brians s series. The outer most protector, got hung up on the butterfly knee pad when he stood back up. It wanted to lift the whole pad up. Could have cut the outer protector off, to exactly resemble the revoke 9000 knee pad. But instead just put the Revoke knee pad on the Brians, and put the Reebok on MY Vaughns. I don't have the same problem on the Vaughns. The Knee cradle is wider.Strapped up tighter on the lower velcro strap the pad can't fall ,past the calf muscle. Stays in place.