The Back on Track® Royal Hock Boot with padded lining has been designed to fit snugly and securely to this hugely important but often difficult-to-wrap joint. The Welltex™ lining is 50% cotton and 50% polyester with 100% polyester filling, while the outer is sturdy neoprene and the boot is secured in place with hook and loop straps. Designed to deliver the benefits of reflected infrared where it is most needed, the Royal Hock Boot supports suppleness and flexion and is ideal for horses with hock problems. Packed in pairs, in four sizes. Small: Circumference at top 42-45cm, circumference at bottom, 30-34cm. Medium: Circumference at top 40-47cm, circumference at bottom, 32-37cm. Large: Circumference at top 44-49cm, circumference at bottom, 36-40cm. XL: Circumference at top 47-51cm, circumference at bottom, 38-41cm. Measurements are taken 5cm from the pad at the top and bottom.