Power Pills are "thermostatic actuators" that are a compact, durable and reliable power source which instantly transforms heat energy into piston-driving mechanical energy. Most commonly identified by their application in automotive thermostats, they are also used in many other applications ranging from position dampers to pneumatic control to liquid flow control. They are activated by temperature changes and can withstand severe vibration and fluctuating pressures.

In operation, the wax charge mixture heats rapidly, it expands, pushing a diaphragm against an elastomer stem seat and driving the piston/stem. Fulton 's proprietary process suspends heat transfer powder in the sealed wax charge so the charge response will not deteriorate over time. Operating temperatures and strokes may be specified and a wide range is available, from up to about 250 F and 0.6 inches, respectively. Each Power Pill is calibrated at the factory to give a particular stem height at a given load specified by the customer.