Mixim 1 PCS 11T MTB Bike Road Bicycle Ceramic Bearing Pulley Rear Derailleur Jockey Wheels for Shimano & Sram XX, XO, X9, X7 Black 11T Ceramic Bearing Jockey Wheel Rear Derailleur 11T Tooth Road MTB Jockey Wheels Black color 4mm/5mm/6mm Axis Compatible for Shimano Sram XX X9 X7