Zero Alpha is state-of-the-art digital engine speed governor for model helicopters which automatically monitors the speed and maintains constant RPM. It not only works very well in all maneuvers, but also has a very user-friendly interface and easy to setup. The Zero Alpha is designed to govern the engine speed between 10,500 and 21,000 RPM. Like all the PCM radio accessories, this governor will only work while a transmitter signal is received.