[Strong Function]– Specially designed with the swing arm; the chain then runs over it to keep it aligned [Suitable Fitment]– Inner diameter: 10mm, can also be used on gas petrol motorized bicycle conversions kits [Good Quality]– This Pulley Chain Roller is made from the high quality materials, sturdy and durable for long time service [Convenient Use]– The chain roller wheel complete with heavy duty bearings very easy to use [Warm Prompt]– 10 mm Inner Diameter, Please check the size and confirm this chain roller meet your need Note: Please allow 1-3 mm error due to manual measurement. Thanks for your understanding. Monitors are not calibrated same, item color displayed in photos may be showing slightly different from the real object. Please take the real one as standard. Please be carefully check the parts appearance, size, shape and then compare your original goods for compatibility before your order!