10 pulleys in one set. Made of iron and plastic, with ball bearings inside, smooth running and durable. Suitable for your wardrobe, bookcase, glass cabinet and other office furniture. Note: The wheel diameter is 19mm, please check the size of your furniture to make sure the pulley can meet your needs before purchasing. This caster is made for U-shaped rail Diameter of each caster: 1.8cm. Width between two castors inner dimension: 1cm. Overall dimensions (width): 1.9cm. Thickness of the wheel: 0.4cm The castors have a small support to place and wedge the door correctly before fixing it. Even 2 and 50 meters high doors slide well Although small in size, enough to support about 40 kg Note: The data are all measured manually, please allow 1-3 cm error due to differences in light and display, there may be some color differences, please refer to the actual item received.