Hydrogenated nitrile (HNBR) is NBR with the polymer backbone saturated through hydrogenation, which removes the double bonds that make standard nitrile vulnerable to heat, ozone, and sour gas. The result is a compound that keeps the oil and fuel resistance of NBR while extending continuous service to roughly 300°F (150°C) and standing up to H2S, amines, and steam far better than its base polymer. Moss Seal supplies HNBR in a range of hardnesses and ACN levels, including peroxide-cured grades qualified for rapid gas decompression service. It is the usual step up from NBR for downhole tools, wellhead equipment, and any application where nitrile is hardening or failing early on temperature or sour exposure.