Features: This Bicycles single speed chain tensioner effectively prevents chain derailments, maintaining stable tension. Make from Aluminum Alloys and steels, with durability and high strength, ensuring long terms performances. This chain tensioner provide a simple, effective and adjustable way to ensure perfect chain tension. Our bike chain Tensioner is designs for quick and easy setups, requiring only a few step to install. Ensures a smooth, quiet Cycling, allowing you to enjoy the sounds of natures without noise chain. Specifications: Materials: Aluminum Alloys and steels Number of teeth: 12T/13T/14T/15T/16T/17T/18T/19T/20T/21T/22T Size: as shown in the picture Package Includes: 5PCS Spacer 1pc Flywheels Cover 1pc Flywheels 1pc Chain Tensioner 2PCS Wrenches 1pc Torque Adjuster 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.