1 set of left and rightThick padding at kneeVentilation holes on the back of the knee are breathable and non-stuffy. Size S: Length approx. 8.7 inches (22 cm), Width approx. 6.3 inches (16 cm), Size M / L approx. 9.1 inches (23 cm), Width approx. 6.7 inches (17 cm), Size XL approx. 9.1 inches (23 cm), Width approx. 7.3 inches (18.5 cm).