Features: Make from aluminum alloy and nylon with fiber, not easy to rusts, ensuring durability. Prevent the chain from falling off, avoid chain interferences while driving, protect the chain and extend the service life. Enhances chain efficiency by reducing wear, prolonging chain lifes and reducing noise. Suitable for mountain bike, road bike, folding bike. it can also be used as a replacements for your old or break chain. Simple to install, light in weight, and small. none more worry about the chain falling down during Cycling after installation. Specifications: Component: Aluminum Alloy and Nylon with Fiber Type: CS04/CS01/CS02 Size: As Shown in the Picture Applicable: 30-40T Single Disk Package Includes: 1pc Chain Guide note: Please allow 1-2cm errors due to manual measurement, make sure that you do not mind before you order. Due to the difference between different monitors, the picture may not reflect the actual color of the item.