With a lightweight shell made from rigid plastic foam that contains 1.1 pounds of extinguishing powder, the Elide Fire Ball is a self-activating fire extinguishing system from Trailer Alarms that covers 19 square feet. At 4 inches in diameter, the Elide Fire Ball fits into nearly any space and is ideal for engine compartments, enclosed car trailers and boats. The mounting brackets were developed for cars and boats, and even off-road racers have been using them. Check out a video demonstration on how they work. $95.