"Plugs" for traditional fan heaters are often unavailable; located between engine and firewall. This tool only requires cutting the hose between the engine and the lower radiator, clamping it, routing the wire and filling it with coolant. 600 watts isn't much, but my wife noticed that she had an air temperature of 70Β°F almost immediately when she started her engine, and that was the end goal. Convection heats the motor sufficiently without breaking down moving parts.