EXTREME TECHNOLOGIES CORP. FireStopper Firefighting Catalyst can be used on all fires except Lithium and Sodium Metals. Usage is 1/4% to 100% as needed. One agent for ALL Fires. FireStopper AB is designed to be used on non-polar fires, using fresh, brackish or salt water. Superior Class A & B retardency not found in any foams, gasses or powders.