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.Speed: 810 rpm or less; Bearing weight: 81 KG.4.U-shaped pulleys suitable for doors, windows, cabinets and other furniture.5.The item contains 8 pieces U Type Groove Guide Pulley Ball Bearing, it will be a good replacement for your doors, windows or other furniture.Specifications:Material: Engineering plastics Bearing SteelColor: WhiteSize: 2.7x0.6x0.9 cm/1.062x0.236x0.354 inch(OD x ID x Thi)Slot width: 6.4mm/0.251 inchGroove depth: 3.2mm/0.125 inchGroove arc: 3.2mm/0.125 inchSpeed: 810 rpm or lessBearing weight: 81 KGWeight: 54 gPackage include:8 x U Type Groove Guide Pulley Ball Bearing Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.