Description: Bike rear derailleur pulley is made of high quality ceramic bearing + aluminum alloy material, whcich is anti-rust and corrosion resistant, sturdy and durable. The inner ceramic bearing is ultralight and super lubricating, which can ensures its smooth working and provide you with a great using effect. The rear derailleur pulley is used on rear derailleur for chain transportation and speed changing, which is a necessary accessary for bicycle. Deep toothed guide wheel to reduce chain drop. Positive and negative tooth guide wheel can effectively inhibit the horizontal swing of the chain, so that the speed is more accurate Easy to install, included a screw and 2 replaceable 4mm and 5mm bushing to enrich your installation choices. Specification: Material: Aluminum Alloy, Ceramic Bearing Size: 11T - 41.4mm/1.63inch 12T - 50mm/1.97inch 13T - 50.7mm/2inch 14T - 58mm/2.28inch 15T - 59.7mm/2.35inch 16T - 68mm/2.68inch 17T - 66.8mm/2.63inch Package Includes: 1 Piece Bike Rear Derailleur Pulley Wheel Note: 1. Due to the light and screen difference, the item's color may be slightly different from the pictures. 2. Please allow 1-3mm differences due to manual measurement.