Shaped Stirrup Irons - Otherwise known as the Australian simplex, these Shires Bent Leg Stirrup Irons have been designed to help prevent the foot becoming caught in the stirrup in the event of a fall. Note: irons should be chosen according to foot size, 1.25cm of space either side of riding footwear is correct. Available in 6 sizes. The size refers to the width of the stirrup iron.