Volleyball kneepads are sized according to calf and thigh measurements, so pick the pads that fit snugly but comfortably. adidas volleyball kneepads come in small, medium and large sizes. Use a tape measure around the center of your calf and/or lower thigh to find your size. Small/medium is sized for 11" to 14.5". A large/extra large is sized for 14.5" to 18". Choose a smaller size for a tighter fit or a larger size for a looser fit.