Features1[Durable Material] Made of high quality aluminum alloy and POM steel material, light weight, wear resistant, can be used for a long time. 2[Application] For Brompton special rear derailleur can replace for Brompton original rear derailleur as a whole, and help the chain to prevent the chain from falling off more effectively. 3[Fitment] The number of teeth is 10T, which is fit for 3sixty and other internal variable speed folding bike. (single speed, internal 3 speeds, external 2 speeds, internal 5 speeds and internal 8 speeds) 4[Simple To Use] The folding bike chain guide tensioner is easy to use and does not put extra burden on the bike, so you can use it with confidence. 5[Widely Use] Suitable for bicycle chain tensioning, can be used in mountain bike, road racing, fixed bicycle, single speed bicycle, etc.SpecificationItem Type: Bike Chain TensionerMaterial: Aluminum alloy+POMNumber of Teeth: 10TFitment: Fit for 3sixty and other internal variable speed folding bike (single speed, internal 3 speeds, external 2 speeds, internal 5 speeds and internal 8 speeds)Application: For Brompton special rear derailleur can replace for Brompton original rear derailleur as a whole, and help the chain to prevent the chain from falling off more effectivelyWeight: Approx. 320g / 11.3ozPackage List1 x BikeChainTensioner2 x Wrench