Amerex Halon 1211 Fire Extinguishers feature solid steel cylinders with all metal valves and use all recycled gas in accordance with the Montreal prototcal. Halon 1211 is a liquified gas, pressurized with nitrogen, which discharges as a vapor causing no cold or static shock. Penetrates quickly for hard to see and hard to reach areas and leaves no residue. Recommended for protection of delicate, sensitive and expensive computers, electrical equipment, tapes and film, automotive and aircraft engines, laboratory chemicals, and equipment.