Lateral Extensions used for: Toe in Ankles (Varus) fetlocks, Bowed and Offset Knees, Bowed Hocks. Optimal correction requires early application. (Birth to 2 months due to early physis closure.) Medial Extensions used for: Knock Knees (Valgus), Valgus Hocks (Early correction offers better response.) EXT1: Fits foals 1 to 6 weeks, Max foot width 3" EXT2: Fits foals 6 to 12 weeks, Max foot width 3.5"