Electric systems are activated by pressing a strategically mounted momentary push button. Using a military specification actuator to detonate the extinguisher, the actuator protracts a steel pin upon activation breaking a frangible seal in the neck of the cylinder and thus discharging the contents. All electrical systems have their own independent power supply called a power pack that has facilities for checking the battery strength and circuit continuity as well as giving a visible indication that the system is armed.
For touring and rally cars there is no better foam-based system.