Gyro
This is described by many as the "most cost effective" stabilisation gyro on the market at present. It's job: keep the machine pointing in the direction you want it to. In the old days, you would program a "revolution mix" into your radio which altered the tail rotor blade pitch according to what you were doing with the throttle/collective, the idea being that you could match the rotational energy being put out by the main rotors to make the tail rotor counteract it, and keep the machine steady. Technology these days simply measures the rotation and does what it needs to counteract it. Funky. This is what makes the difference between whirly-top-with-dangerous-bits and simply "dangerous".