Features:Used on rear derailleur for chain transportation and speed changing.11T suits for 8/9/10/11 speed rear derailleur.Inner ceramic bearing is ultralight and owns high degree of lubrication, which can ensures its smooth working.Aluminum alloy construction is anti-rust and corrosion resistance, durable for long time use.2 replaceable 4mm and 5mm bushing is included to enrich your installation choices.A necessary accessary for your bicycle.Specification:Condition: Brand NewMaterial: Aluminum AlloyTeeth: 11THole Diameter: Approx. 6mm / 0.24in(4mm and 5mm bushings are included)Size: Approx. 4 * 0.8cm / 1.6 * 0.3inWeight: Approx. 18gPacking List:1 x Bike Rear Derailleur Pulley2 x Bushings(4mm and 5mm)Note:Please allow slight size inaccuracy due to manual measurement and we appreciate for your understanding..