Features: Designs to provide a simple, effective and adjustable way to tension a single speed. Make of Aluminum Alloys materials, light weight and practical to use. Suitable for mountain bikes and folding bikes, it provide stable chain tension and ensures a smooth and enjoy cycling experience. Equipped with a 11T guide roller, this chain tensioner offers precise and smooth chain movement. With double spring chain guide that minimizes chain slap and vibrations, a quiet and enjoy biking experience. Specifications: Materials: Aluminum Alloys Color: Black/Purpleness/Green/Pink Size: about 10x5cm/3.94x1.97inch Package Includes: 1Pc Mountain Bike Chain Tensioner note: Please allow 1-2cm errors due to manual measurement, make surely that you not mind before order. Due to difference between different monitors, the picture may not reflect the actual color.