Increases the gear-shifting efficiency by reducing the weight pressure applied to the rear derailleur. Fit with Shimano Dura Ace R9100/9150, Ultegra R8000/R8050. Won't fit Shimano Dura Ace 7800, 7900,7970,9000&9070; Ultegra 6700,6770,6800&6870; 105 (5600,5700,5701,5800) or Tiagra (4600&4700).
eBay