Panda Software SENQI 11T Bicycle Rear Derailleur Pulley Jockey Wheel for Shimano/Sram/Campagnolo Anodised CNC machined bicycle jockey wheel with sealed bearing for center bolt derailleurs. 11 teeth bicycle rear derailleur accessary for Shimano/Sram/Campagnolo. Collar diameter is 4mm,5 mm and 6mm, please confirm whether suitable for your bike Dimensions: Width (thickness): 8.5mm, Bolt hole ID: 4mm,5mm and 6mm Diameter: 42mm Packing included:1 x SENQI bike 11T jockey wheel