Cellular rubber is closed-cell foams made of rubber. Cellular rubber is available in different hardnesses or densities. The densities are between 70 and 200 kg/m3. The hardness range varies from Shore OO 28 to 60. The types of rubber available in cellular rubber at HTR are: EPDM, neoprene, NBR, silicone. Cellular rubber is moulded into block shapes and then slit to the right thickness and connected to form rolls. As a result, there are glue connections every few meters in a roll. The sealing quality on these connections is less compared to the rest of the cell rubber. If desired these connections can be detected and taken out.