Bicycle Small Parts ZTTO Folding Bike Bicycle 2/3/6 Speed Rear Derailleur CNC Chains Tensioner Adjustable Stabilizer Aluminium Alloy Transmission Stabilizer This product adopts CNC technology, fine quality and light weight. Effective control chains to prevents falling off when changing speed. Features: Made of fine quality materials, practical. Designed to provide a simple, effective and adjustable way to tension chains and speed change. Does not worry about rusting due to the weather, thus increasing the service life. Help control the chains more effectively to prevents the chains from falling off. Compact structure, compact and convenient, easy to install. Specifications: Product name: compatible with Brompton rear derailleur chains tensionertensioner Material: aluminum alloy Process: CNC processing Item size: 180mm / 7.1in Item weight: 145g / 5.1ounce Package size: 200 * 200mm / 7.9 * 7.9in Package weight: 160g / 5.6ounce Packing List: 1 * Rear Derailleur Chains Tensioner