It monitors your engine RPM to keep a constant head speed. Basically, you plug your throttle servo into a governor and plug that into the throttle channel of your reciever. It has another plug that goes to a channel in the reciever so you can turn it on and off. They all have different functions but basically you program it for the head speed you want to maintain and when you turn it on it controls your throttle servo. As you work the collective it will operate the throttle to help keep you from bogging or over reving your blades.