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, 4/5/6 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% brand newItem type: Bike Rear Derailleur PulleyMaterial: aluminium alloyColor: colorful11T diameter: Approx. 41mm/1.6in13T diameter: Approx. 49mm/1.9in Specification: applicable to the guide wheel of 4/5/6mm 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 x Bike Rear Derailleur Pulley