Stylrtop 2 pcs 11T Aluminum Sealed Bearing Jockey Wheel Rear Derailleur Pulley for Shimano Sram Rear Derailleur Etc. Anodised CNC machined bicycle jockey wheel with fully sealed bearing for center bolt derailleurs Specification:SHIMANO & SRAM Fits for almost all mountain bike of 11T Bearings: Upgraded RS bearingMaterial: Aluminum alloy Stainless steel bearing for ultra durability