Specification Brand : Hyuduo BulletPoint1 : 【Premium Material】These pulleys are made of high-quality materials, durable, strong and durable, and have a long service life. BulletPoint2 : 【Good Performance】These pulleys are internally lubricated, run smoothly, and have a good quiet effect. The U-shaped groove design and smooth surface reduce friction. BulletPoint3 : 【Scope of Application】There are a total of 4 pulleys in a set, you can use them for many projects, widely used in doors and windows to track and drive mechanical equipment. BulletPoint4 : 【Safe to Use】The product is manufactured in accordance with strict quality standards before leaving the factory, with good safety performance and can be used with confidence. BulletPoint5 : 【Quality Service】We strive to provide you with high quality and convenient service. You are welcome to contact us if you have any problem about our product, we will give you a satisfactory reply. ExternallyAssignedProductIdentifier1 : 713135837709 ExternallyAssignedProductIdentifier2 : 0713135837709 ExternallyAssignedProductIdentifier3 : 00609788946090 IncludedComponents : Precision Balls ItemDisplayWeight : 0.07 pounds ItemName : 4pcs 0840UU U Type U-Groove Pulley Roller Plastic Coated Guide Wheel Bearing 8x40x20.7mm ItemPackageDimensions_Height : 14.3 centimeters ItemPackageDimensions_Length : 4.2 centimeters ItemPackageDimensions_Width : 10.7 centimeters ItemPackageQuantity : 1 ItemTypeKeyword : deep-groove-ball-bearings Manufacturer : Hyuduo Material : Ceramic,Metal,Steel Material1 : Plastic Material2 : Metal ModelNumber : Hyuduovik72rgd30 NumberOfItems : 2 PartNumber : Hyuduovik72rgd30 ProductDescription : Features: Made of high quality material, these pulleys are durable, sturdy and wearable. Internal lubrication grease, smooth operation, good mute effect. U-shape groove design, smooth surface reduces friction. There are total 4 pieces of pulleys in one set that you many use for many projects. Widely used in doors and windows to track and drive mechanical equipment.