Foam rolls come in a variety of widths, thicknesses and lengths. The thinnest foam comes is 1mm and the thickest is 4mm. The thickness of the foam also dictates the length on the roll. Sizes shown are in width , length on the roll and then lastly the thickness of the foam Please note that the foam can be slit to 300mm, 400mm, 500mm, 600mm and 750mm if required.