Tough-1 Vented Sport Boot Rear Designed to fit snug against leg to keep out water, mud and dust. One piece, user friendly design provides extra support. Contour design supports fetlock area. Double layer of air-flow (vented) neoprene. Single tab swith quick-grip" closure for easy on/off. Tab extension is easy to grip when removing and locks large tab in place. Size: Medium/Average Horse (800 - 1,100 lbs.)