Size: Bearing inner diameter: 21mm / Inner diameter: 6mm / Wheel diameter: 50mm / Thickness: 18mm / Axle length: 36mm. Installation: Simple luggage casters, can be installed by yourself without professional guidance, very convenient. During installation, please also ensure that the wheels are firmly seated to ensure the luggage casters glide better. Advantages: High-quality replacement wheels. Durable, quiet, load-bearing, double bearings, flexible rotation. Load: A single suitcase can bear up to 51kg, without deviation phenomena, ensuring safe and reliable use. Cleaning: The replacement suitcase wheels are easy to clean and the wheels can be removed for cleaning. Buyers need to measure the following data of the suitcase wheels to know what size they can roll: 1. Measurement of the wheels with original outer diameter (wheel size). 2. The inner width of the measuring wheel groove (width of the entire installed width). 3. By the length micrometer (without nuts on both ends). 4. Measured