Closed-cell foamed gasket materials include silicone foam as well as cellular rubber. In closed-cell materials, the cell walls are closed, which means that the cells of the material are not connected to each other and these materials are considered waterproof and airtight. Open-cell materials, on the other hand, are characterized by open cell walls, which allows sound and water in particular to be absorbed very well. A combination of closed-cell and open-cell is called mixed-cell. Our sponge rubber, thanks to the outer skin that protects the material from moisture, is considered mixed-cell.