This material is natural rubber with little complex rubber. It was pressed by bond and high temperature. 1. It was added complex rubber, so this product can get more security and coziness. 2. This product was designed for impact resistance, noise resistance, water resistance, fire resistance. 3. Be satisfactory price. 4. More convenience of construction than coil series. Be plentiful colors, be modern space. This product isplentiful colors, also bepolychrome individual space.