Features: Made of rubber and metal material, durable and wear resistant. Strong load-bearing, mute design, rotating flexible. Sliding effort, without effort, than the luggage wheels are easy to use. Easy to transform to any directions that you want, and spend little strength to move on. Long-term use, low wear, labor-saving and quiet, flexible rotation, large load capacity and stability. Specifications: Item type: luggage wheel Material: rubber + metal Color: black Size: about 50mm, 60 x 18mm Package includes: 4pcs x wheels 4pcs x axle 4pcs x screw 4pcs x wrench 8pcs x gasket Notes: Transition: 1cm=10mm=0.39inch 1. Due to the different monitor and light effect, the actual color of the item might be slightly different from the color showed on the pictures. Thank you! 2. Please allow 1-3cm measuring deviation due to manual measurement.