LONG-LASTING SERVICE - Made of nylon and stelle, these swivel casters are wear-resistant and durable for long-lasting use. Key Product Features 8mm STEM CASTORS --Measure the stem diameter of your old chair before buying it. Stem length: 20mm, Thread size: M8/8mm, Wheel diameter: 50mm, Wheel height: 80mm. Easy to install and no tools required: remove your old office chair casters and push your new wheels in until that the rod is firmly held and secure. Smooth and Quiet - With a double wheel that allows the wheel to spin and turn fully, these braked swivel casters allow you to easily move heavy furniture around any room. direction. Less floor damage, and quiet, suitable for hard floors such as parquet, laminate, ceramic tile, PVC, etc. Wide applications--Maximum capacity weight is 18kg, the wheel is suitable for shelves, bookcases and household appliances.