No longer must you fight through the pain while slowly cultivating callouses on your heels. Dial in an absolutely perfect heel cup fit on your shoes with the Sidi Adjustable Heel Retention system. Fitting just above the plastic heel cup on any current or past model of Sidi's Dragon, Genius, or Ergo shoes, the Heel Retention System may be tightened or loosened with the simple turn of a screw, ensuring a comfortable, performance-enhancing fit. Also retrofits to any shoe model with the non-adjustable Heel Security System.