Herm Sprenger System 4-F Bow Balance Stirrup Irons are designed to significantly reduce strain on knee and ankle joints. They pivot simultaneously in four directions to allow for greater comfort and improved performance. This increased flexibility helps alleviate tension and pain in the hips, knees and ankles by softening the impact on joints, cartilage and ligaments. Manufactured according to strict standards and using only the highest quality materials, these irons have a wide, shock-absorbing footbed. The bowed shape and offset eye help hold the iron in the correct position for optimal foot placement. All stirrups are marked left and right to accommodate the anatomical shapes of your left and right leg. Cut-out branch eliminates unnecessary weight.