Feature:1. Equipped with a hole diameter 4mm sleeve, original hole diameter 5mm, if the original sleeve is removed, the hole diameter can be changed to 6mm, 4 or 5 or 6 shaft pulley screw can be applied.2. Made of high quality materials, durable and practical.3. Easy to install and use, provide good usage experience.4. Wonderful accessory for mountain bike.5. 2 different types for you to choose, meet your different needs.Specification:Condition: 100 percent brand newItem type: Bike Rear Derailleur PulleyMaterial: aluminium alloyColor: colorful11T diameter: Approx. 41mm or 1.6in13T diameter: Approx. 49mm or 1.9inSpecification: applicable to the guide wheel of 4 or 5 or 6mm axes.Guide wheel selection rules:Please try to choose the same as the original guide wheel, if there is no same, you can choose smaller than the original guide wheel, can not choose a larger one.Applicable: for SRAM and micro rear derailleur.Package List:1 Set xBike Rear Derailleur Pulley