Features Material----> Made of high quality POM material, these wheels are durable and sturdy. Wear resistance---->Wheels have good physical, mechanical and chemical properties, especially have great wear-resistance. Parameter---->The bearings in these wheel are 625, with a 5mm inner diameter. Feature----> There are total 20 pieces of wheels in one set, which you may use for many projects. Application---->They are normally used for 3D printers, CNC machines and many other machines. Features: Made of high quality POM material, these wheels are durable and sturdy. Wheels have good physical, mechanical and chemical properties, especially have great wear-resistance. The bearings in these wheel are 625, with a 5mm inner diameter. There are total 20 pieces of wheels in one set, which you may use for many projects. They are normally used for 3D printers, CNC machines and many other machines. Specifications: Main Material: POM Shape: V groove Bearing Type: 625 Inner Diameter: 5mm Quantity: 20pcs Weight: 253g(approx.) Package Includes: 20 x Wheels Package List