Quality Test Standard(ABS+PC Material)size20inch/18kg24inch/20kg28inch/25kgDrop Loading Test4Wheels:3Times/90CMFour wheels roll smoothly,No damage2Wheels:1Time/60CMFour wheels roll smoothly,No damage1Wheel:4Times/60CMFour wheels roll smoothly,No damageProtective pads:3Times/90CM No Breakage,Stay strongMaterial:Twice/90CM Retian good shape and formFour Corners:3Ti...