Unlike dry chemical systems, these portable extinguishers leave no residue whatsoever The fire-suppressant agent is a non-conductor of electrical current Provides ideal extinguishment capabilities for flammable fluids including gasoline and diesel fuel Fully effective on galley fires 5lb.Fireboy portable fire extinguishers are the first clean-agent systems in the world to receive U.S. Coast Guard approval.A unique feature of these portable fire extinguishers is super pressurization using Argon gas that enables a user to stand as far as ten feet away from a fire. Applied directly to engines, it causes no cold shock as with carbon dioxide extinguishers and thus will not damage the engine or component parts. Upon release, the agent turns instantly into a "heavier than air" gas. As such, it tends to settle and remain in an enclosed space such as an engine compartment.UL listed.