These gas cartridges are designed to fit Ansul RedLine cartridge-operated extinguishers. They are available with nitrogen or carbon dioxide for 5, 10, 20, and 30 lb extinguishers. Right-handed (reverse threaded) nitrogen cartridges are used in low-temperature extinguisher models, the remaining models use a left-hand thread. Most of the non-low T models use a CO2 cartridge, but some specialty units use the left-hand nitrogen cartridges. It is critically important that you check your extinguisher nameplate label and owners manual before ordering and installing the cartridges.