Size: Bearing inner diameter: 21mm / X Inner diameter: 6mm / X Wheel diameter: 50mm / X Thickness: 18mm / X Axle length: 36mm. Installation: Simple luggage rollers, without professional instructions, can be installed by yourself, very convenient. Also pay attention to the tightness of the wheel when installing, so that the luggage rollers can roll better. Advantages: High quality replacement wheels. Durable, quiet, load-bearing, double bearing, flexible rotation. Load: A single suitcase can bear up to 51 kg, without deviation of the phenomenon for safe and reliable use. Cleaning: The suitcase replacement wheels are easy to clean, and the wheels can be removed for cleaning. Buyers should measure the following suitcase wheel data to know what size they are able to roll: 1, measuring the original outer diameter wheels (wheel size). 2, the inside of the measuring wheel groove width (width of the total installed width). 3, through the length measuring screw (without nut at both ends). 4,