PREMIUM MATERIAL: This pulley is made of CNC aluminum alloy, which is lightweight, durable and has a long service life.GREAT WORKMANSHIP: The bicycle guide wheel pulley is anodized anti-rust and corrosion resistant. So it can be used for a long time with good performance.SUITABLE FOR USE: This pulley works with smooth ball bearings, it is a must-have accessory for your bike. It fits almost all 11T or 13T mountain bikes. Hope you enjoy your cycling.MINI SIZE DESIGN: The pulley is lightweight with compact size, which is easy to carry and store. There are four different colors to choose from to meet different needs.GUARANTEE: If you are not satisfied with the product you received, you can email us at any time. We will answer you instantly and help you solve your problem.Technical descriptionColorBlackSize11TBatteries included NoManufacturer reference62ewp9vnhq-06ASINB07MNMGD1G Features: CNC aluminum alloy jockey wheel with central bearing. Super light, weighs only 11 grams. Compatible with Shimano 11 teeth rear derailleur. Specifications : Material: Aluminum Alloy Color: Black Inner Diameter: About 5.2mm Weight: 11g or 0.4 oz Package List: 1 x Derailleur Pulley