Nitrile rubber is a synthetic rubber co-polymer of acrylonitrile and butadiene. Also known as Buna-N or NBR, Nitrile rubber is resistant to aliphatic hydrocarbons, oils and fuels; and has a temperature range of -20 °C to + 100°C. It is similar to commercial and natural rubber, as it can be attacked by UV/Ozone. Nitrile is popularly used in the aeronautical, petrochemical and automotive industries as O rings, gaskets and seals.
An open cell sponge is exactly what it seems: it's a product that soaks up and traps liquids. Used in kitchens and tough cleanup situations, the openly interlinked chambers absorb liquids, dampen hard impacts, and generally act as a good padding solution. The closed cell variant functions as a gap filler, a noise and vibration attenuator, and even as a seat cushion.