UA Armour 2.0 Knee Pads Super durable circular knit construction for unmatched comfort, fit & feel. Dual density EVA foam for increased impact protection. Hinged design allows for maximum mobility. Small: 10.2"? Top Circumference, 9.1"? Bottom Circumference. Medium: 11.4"? Top Circumference, 9.8"? Bottom Circumference. Large: 12.6"? Top Circumference, 10.6"? Bottom Circumference.