Upgraded accessories: The material is environmentally friendly PU material,The addition of a meson can be applied to 8mm holes. Wide Applications: replacements for worn-out luggage suitcase wheels or as a back-up set just in case. Size:Center Bearing Internal Diameter Is 6mm. 360 Smooth and Quiet:They have a 360-degree rotating design that makes every turn a lot smoother and easier to manage. And they can roll smoothly and quietly on virtually any ,so you 't be bothered by the constant noise. Material:Our wheels are made of Environmental protection PU .They have the hard-wearing design. And to dirt and for a long-lasting effect. Easy To Install:The Wheels Were Easy To Install and Works Great: 1. Use A Hacksaw To Cut Off The Pole Which Connects The Wheels. 2. Put On The With The Included Accessories. Colour:black Material:PU Size:50X15mm Package Contents: 8x Luggage Wheels Replacement 8x axles and screws 8x meson 8x wrench 16X Gasket Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.