Features: 1.Every product has a special Manufacturing Part Number label on the inner kit that proves it has been qualified,which consist of Part Number,Model Number and inspection date information;2.If you've any questions about the item,please provide us the Manufacturing Part Number for checking,your profits could be guaranteed.3.Single Groove Pulley: Diameter: 31mm/1.22"; Aperture: 8mm/0.31"; Thinkness: 15mm/0.59"; Step Diameter: 16x6mm/0.63"x0.24"4.Suitable timing belt: 3-5mm round belt; often used as unpowered spindle of DIY small drilling machines, milling machines, and small lathes.5.Suitable for health club equipment, ball mills, etc., and can be used with DC tools motors.6.Made of aluminum, it is lightweight, ultra durable, rolls smoothly, and can be put in on the surface or within the air.7.Transmission Round Belt: Length: 1000mm/3.28ft; Diameter: 5mm/0.2" compatible for unmarried groove pulley transmission.Specifications:Material: Aluminum AlloyColor: Silver & GreenBrand name: BQLZRSize:Single Groove Pulley:Diameter: 31mm/1.22"Aperture: 8mm/0.31"Thinkness: 15mm/0.59"Step Diameter: 16x6mm/0.63"x0.24"Transmission Belt:Length: 1000mm/3.28ftDiameter: 5mm/0.2"Weight: 40gPackage include:1 x Single Groove Pulley1 x Transmission Round Belt