1. Applicable models: for INOKIM OXO OX electrical scooter 2. The bearings are made of high quality steel material, rust-proof and durable 3. Fine processing to ensure smooth surface and smooth rotation, more suitable for your scooter 4. Not easy to corrode, easy to adapt to the harsh riding environment 5. Maintenance-free design saves time and energy, enjoy a more comfortable riding experience 6. Outside diameter: about 4.7cm