The Alpha knee sleeve uses a breathable perforated neoprene with air plush lining for the front section while the back side uses a dual layer of soft Lycra for extra comfort. To keep them super slim & flexible we use EVA foam padding to protect your knees from impact. This year we also added a Sharkskin neoprene gripper to keep the pad firmly in place. Features Breathable perforated neoprene with air plush lining, back side with dual layer Lycra & EVA foam padding.