Features: 1.Inner diameter: 8mm 2.Brand new chain rolloer 3.Dirtbike nylon chain roller wheel complete with heavy duty bearings ready to use 4.This part attached the the swing arm; the chain then runs over it to keep it aligned 5.Vary colors for you to choose your favorite one Specification: Features: 1. Brand new chain roller. 2. Dirtbike nylon chain roller wheel complete with heavy duty bearings ready to use. 3. This part attached the swing arm; the chain then runs over it to keep it aligned. 4. Can also be used on gas petrol motorized bicycle conversions kits. Specifications: Inner Diameter: Approx. 8mm / 0.31" Outside Diameter: 3.5cm / 1.38" Total Length: 3.5cm / 1.38" Package Weight: Approx. 55g Optional Color: Yellow, blue, green, red Package Included: 1 x Drive Chain Roller Note: 1. Please allow 1-3mm error due to manual measurement. Thanks for your understanding. 2. 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. 3. Please be carefully check the parts appearance, size, shape and then compare your original goods for compatibility before ordering, Thank you. PackageList: Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.