Easy to put on knee support Molded padding conforms to the shape of the knee. Designed to bend and move around in. Size: For boys (A20cm, B17cm, C 13.5cm, Upper Portion: 22-35cm, Lower Portion: 24-35cm) Small (A 21cm, B 19cm, C 14cm, Upper Portion: 27-36cm, Lower Portion: 27-36cm) One size fits most(A 25cm, B 20cm, C 16cm, Upper Opening 30-4 cm. 5cm, bottom opening 11.8 - 17.7 inches (30