LeMieux Derby ProJump Tendon Boots Black. The LeMieux Derby ProJump Tendon Boots are used on the front legs for protecting the tendon area from strikes from the hind hooves that can occur when the hind leg extends forward towards the front leg. The Derby ProJump offer a jumping boot designed to protect the tendon and prevent any heat building up. The LeMieux Derby ProJump Tendon Boots features: Soft inner lining and flexible cut-away design allow optimum fit. double velcro over-locking closure ensures security. Read more… A Highly recommended product for those jumping horses out there.