Round with a round circle with a band, also known as polyurethane, which can be accessed round with it usually PU material, PU is an abbreviation for Polyurethane, Chinese called polyurethane called polyurethane. Because, you need to simply modify the recipe, you can obtain the physical properties of different density, elasticity, rigidity and so on. At present, a large number of alternative to glass fiber insulation materials, wood, traditional rubber products are widely used