Description Features: 1.Every product has a unique Manufacturing Part Number label on the inner package that proves it has been qualified,which include Part Number,Model Number and inspection date information;2.If you have any questions about the item,please provide us the Manufacturing Part Number for checking,your profits will be guaranteed.3.Made of aluminum, pulley, long time and durable use.4.41MM diameter,12mm aperture,16MM Thickness.5.Suitable for 3-5MM PU round belt.6.Commonly used for DIY small drilling machine, milling machine, small unpowered spindle of machine tool.Specifications:Material:Aluminum AlloyColor:SilverDiameter:41MM/1.61 InchAperture:12MM/0.47 InchThinkness:16MM/0.63 InchStep Dia:20MM/0.79 InchOverall Size:41x16x12MM/1.61x0.63x0.47 Inch ( OD x T x ID )Weight:28gPackage include:1x Pulley