Boot Sizing: Measure around leg halfway between the knee and fetlock Small = under 7" Medium = 7" to 8" Large = 8" to 9" Extra Large = 9" to 10" The H10 Support Boot combines the most advanced materials in sports medicine with a patented design to create the ultimate, multi-use support system. The PRO commitment to bring you the best support on the market is apparent in the attention to detail and materials used in this, and every, PRO product. The Performance Support Boot is constructed of orthopedic grade neoprene for better fit and support. The breathable, shock absorbing foam liner keep the support cooler than other boots while absorbing more than three times as much shock as the competitor. This foam liner is detachable, allowing the use of accessory liners, increasing the utility of the support. The low profile support strap pulls evenly in a bio-mechanically correct fashion allowing the user to adjust the angle and amount of tension to match their horse. All hook and loop surfaces are matched for maximum cycle life and durability. Both the support body and the liner are machine washable. Available in Small, Medium, Large and Extra large in a variety of colors.