Note: The color of the product we ship is the color in the first picture, and the specification and quantity are shipped according to the quantity and specification described in the title. If you need to change the color or style, you need to contact us within 12 hours after placing the order. Our product description: Product 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 POM and bearing steel, good quality and durable.4.Deep groove ball bearings, fashionable, slide flexible, compression wear.5.Size: 50mm(Dia),8mm(Hole Dia),7mm(Groove width),12mm(Thickness),5mm(Groove Deep), 3.5mm(radian R),6.One pulley can load 99kg.7.Suitable for your sliding door, windows, printers,sterilizer.Specifications:Product material: Engineering Plastic and Bearing SteelColor: WhiteBrand name: BQLZRSize: 5x1.2x0.8cm or 1.96x0.47x0.31inch(Dia x Thickness x Hole Dia)OD:50mmID:8mmThickness:12mmGroove width:7mmGroove depth:5mmRadian:3.5mmLoading capacity:99kgWeight: 128gPackage include:4x Pulleys Note: Because the model and display effect of the monitor may be different, there may be slight differences in color, and the size is manually measured, there may be an error of 1-2cm, please understand.