These Superior Tendon Bootsare made froma strong protective outer with a perforated neoprene support lining. The boot also has a Gel - Tech Lining to act as a shock absorber when needed. The Zandona Superior Boot also features 6 Air Vents to allow air flow to keep the joints cool and a Flex - Zone st the back of the leg to allow maximum freedom of movement. Fastening with 2 elasticated front closure straps.