These closed cell rubber sponge sheets are made from a combination of neoprene and SBR (styrene butadiene rubber). Sponge rubber is also referred to as cellular or foam rubber. It takes these names because numerous air pockets are dispersed throughout the rubber material, making it softer and easier to compress than a piece of solid rubber. Because these air pockets excel at trapping and dissipating kinetic energy, rubber sponge demonstrates great shock absorbency and sees use in applications for energy absorption and protective rubber padding. These air pockets also ensure that sponge rubber transmits heat at a slower rate compared to solid rubber, making it a suitable material for heat insulation. Due to the sealed nature of the air  pockets in closed cell sponge rubber, this material has a higher compressive strength than open cell sponge. This attribute of closed cell sponge makes it preferable to open cell sponge in padding applications where a rubber piece must maintain its structure while still absorbing kinetic energy. The isolated air pockets in closed cell rubber also make the material far less porous than open cell, preventing the material from absorbing water. Combined with the water-resistant nature of SBR and neoprene rubber materials, this closed cell blended rubber often sees use in aquatic and gasketing applications.