Description:1 Made of high-quality Aluminum alloy material by fine process with durable and tear resistant characteristics, has long life.2 12 teeth bicycle rear derailleur accessary.3 Durable and light-weight, easy to install.4 Fits for almost all mountain bike of 12T.5 Bicycle  wheel with fully sealed bearing for center bolt derailleurs.Specification:Material: Aluminum alloy48mm in diameterSupport 7/8/9/10 speed rear dialPackage included:1pc * Bike rear wheel