Features:1.Made of hard rubber and iron, durable in using2.Black rollers pulley chain tensioner for motorized pit bike motorcycle 8mm3.Dirtbike chain roller wheel complete with heavy duty bearings ready to use4.Inner Diameter: 8mm / 0.31 inch5.External Diameter: 3.6cm / 1.42 inchSpecification:Features: 1. Made of hard rubber and iron, durable in using. 2. Black rollers pulley chain tensioner for motorized pit bike motorcycle 8mm. 3. Dirtbike chain roller wheel complete with heavy duty bearings ready to use.Specifications: Material: Rubber & Iron Color: Black Inner Diameter: 8mm / 0.31" External Diameter: 3.6cm / 1.42" Height: Approx. 2.5cm / 0.98" Package Weight: 47g Package Included: 1 x Chain Pulley Roller Note: 1. Please check the size and pictures carefully before your purchase. 2. Please allow 1-3cm error due to manual measurement. Thanks for your understanding.PackageList: