These chair wheels are mainly made of plastic and nylon, and strong, feature strong bearing capacity. They are easy to install, no special tools need, friendly to people who have little manual skills. The wheels only produce low noise, suitable for office use. Features -Color:Black -Material:PU, nylon -Size:8.10X5.50X5.50cm/3.18X2.16X2.16in -Stem Diameter: 7/16 inch (11mm) -Stem Length: 7/8 inch (22mm) - Smooth rotation: The chair wheels can be rotated freely without obstacle, easy to move, offering you a smooth experience. - Wear resistance: These chair wheels have a in wear resistance, making them and . - Stable stand: The area of between the wheel surface and the ground is large, and the load-bearing force is stronger, safe to use. - Easy to install: You just need to push the stems of these chair wheels into your chair feet, tools needed. - Enough replacement: The replacement chair wheels will help your chair have a longer service life, no need to buy a new one. Package list: 5 wheels