Feature:1. Made of quality aluminium alloy material, wear resistant, sturdy and durble.2. Fine workmanship, make your bike more stylish and cool.3. Ceramic self-lubricating system, good lubricity.4. Suitable for mountain bike and road bike.5. 2 different colors for you to choose, meet your different needs.Specification:Condition: 100% Brand NewItem Type: Rear Derailleur PulleyMaterial: aluminium alloyOptional Color: red, blackTeeth: 13TDiameter: Approx. 49mm/1.9inWeight: Approx. 10gSelection principle:1. Try to choose the same size as the original guide wheel. If it is not the same, you can choose a smaller size than the original guide wheel, and you cannot choose a larger one.2. The guide wheel is not distinguished from the tension wheel. Some of the rear derailleur are different in size from the tension wheel and can be replaced. The chain length needs to be adjusted again..Package List:1 xRear Derailleur Pulley1 x AttachmentNote:Support most of rear derailleur, support 8/9/10/11 speed.