OUTERDO 11T Aluminium Mountain Bike Jockey Wheel Rear Derailleur Pulley for Sram Anodised CNC machined bicycle jockey wheel with fully rubber sealed bearing for center bolt derailleurs. Size: 4.3cm/1.8"(dia), thickness 8.5mm,Hole size: 5mm dia, radius 42mm Made of CNC aluminum alloy, lightweight and durable.Anti Rust/Corrosion Resistant Anodized Stainless Steel bearing for ultra durability 11 teeth bicycle rear derailleur accessary.