Feature:1. Hollow Design: The bike derailleur pulley has a hollow edge that adds a dics friction system to help quickly remove sand and rain2. Strong Support: The bike guide pulley ensures stability and durability, reduces deflection, with strong support, and is not easy to deform3. 11 Teeth: The bike guide wheel is an 11 teeth rear derailleur pulley, with CNC machining and built in lubricated bearings4. Aluminum Alloy: The rear derailleur pulley is made of aluminum alloy, which is durable, not easy to rust, and resistant to corrosion5. Wide Compatible: The bike rear derailleur pulley has wide compatible performance with 4mm/0.16in axle, 5mm/0.2in bushing, rear derailleur pulley screwSpecification:Item Type: Rear Derailleur PulleyMaterial: Aluminum Alloy Package List:1 x Rear Derailleur Pulley1 x Reducer