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 bearing steel and Engineering Plastics.4.OD:10mm, ID:40mm, Thickness: 10mm, Pulley Sphere Radius of Curvature: 5mm, Load-bearing: 83KG.5.Suitable for Doors and Windows.Specifications:Material: Engineering Plastics + Bearing SteelColor: White + SilverLoad: 83KGPulley Sphere Radius of Curvature: 5.5mmSize: 10 x 40 x 10mm/1 x 4 x 1cm/0.39 x 1.57 x 0.39 inch(ID x OD x T)Weight: 107gPackage include:4 x Bearing Pulleys