Item Type: Bike Rear Derailleur Pulley Material: Aluminum Alloy, Ceramic Bearing Product Style: 12T Product Application: Rear Dial Guide or Tension Wheel Support 7-12 Speed Hole Diameter: Approx. 6mm/0.24in Reducing Rings: Approx. 4mm/0.16in 5mm/0.20in 1、DEEP TOOTH GUIDE PULLEY: Bike guide roller pulley is a deep tooth guide pulley with optimized inclined tooth shape, synchronized with the chain drive direction, making the entry and exit of the chain smoother. 2、7?12 SPEED SHIFTING SYSTEM: Bike derailleur pulley reduces lateral misalignment, which shortens shift response time and improves shift performance. Suitable for 7?12 speed shifting system. 3、IMPACT RESISTANT: Bike guide wheel is made of full aluminum alloy, impact resistant, anodized surface, effective protection of aluminum alloy body, anti corrosion and anti oxidation. 4、CNC MACHINING: Bike rear derailleur pulley is CNC machined and finished with a cutter, making the product look and feel better. It can be used for a long time and has a very good performance. 5、MORE EFFORTLESS RIDING: Rear derailleur pulley is not easily deformed by force, resistant to cold, high temperature and corrosion, high transmission efficiency, and more energy saving riding. 1 x Bike Rear Derailleur Pulley 2 x Reducing Sleeve