All That Sport Boots are marked on the inside with Left/Right marking. You place the boot on the leg with the exit from the vertebra. Loosely tighten the three Velcro straps starting from the top down. Adjust the fit and then tighten the sling support loosely under the vertebra by pulling it diagonally up towards the front of the boot. Check the fit and then tighten all four Velcro straps starting at the top. Remember that this is a boot to provide stability and protection from external impact so do not over tighten. It should fit properly with support but not like a plaster cast. The shields also fit well on hind legs but go up a size towards what your horse needs in front. Circumference of the cow! Small: 25,5cm Medium: 28cm Large: 30,5cm Height of the leg shield! Small: 23cm Medium: 25,5cm Large: 28cm