Specification Brand : BQLZR BulletPoint1 : Diameter: 31mm / 1.22" Aperture: 5mm / 0.17" Thinkness: 15mm / 0.59" Step Dia: 16mm / 0.63" BulletPoint2 : Suitable for DIY small drilling machines, milling machines, and small lathes without power spindles. BulletPoint3 : Pulley hole type: fixed hole, with machine screws, you can use a torx drill to tighten the screws, easy to fix and use. BulletPoint4 : Standard V-belt pulley: Bore diameter: 5mm, for a shaft with a diameter of 5mm. BulletPoint5 : The pulley is single grooved. Color : Silver ItemName : BQLZR Aluminum Single Groove Pulley 31mm 5mm Hole Diameter for 3-5mm Belt Pack of 2 ItemPackageDimensions_Height : 1.97 inches ItemPackageDimensions_Length : 4.13 inches ItemPackageDimensions_Width : 3.35 inches ItemPackageQuantity : 1 ItemTypeKeyword : v-belt-pulleys Manufacturer : BQLZR Material : Aluminum ModelNumber : M4230717005 NumberOfItems : 1 PartNumber : M4230717005 ProductDescription : 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.Suitable for DIY small drilling machines, milling machines, and small lathes without power spindles. 4.Pulley hole type: fixed hole, with machine screws, you can use a torx drill to tighten the screws, easy to fix and use. 5.Standard V-belt pulley: Bore diameter: 5mm, for a shaft with a diameter of 5mm. 6.The pulley is single grooved. 7.Suitable for gym equipment, ball mills, DC gear motors, etc. 8.Made of aluminum, it is lightweight, extremely , rolls smoothly and can be floor mounted or suspended.