The G402's "Fusion Engine" pairs a sensor accurate at low inch-per-second movement speeds with an accelerometer that's very accurate at high movement speeds.
Said senior engineer François Morier: "We had to make an arm that was spring operated, because at the beginning of the project we just wanted to have a very basic arm to validate, to be able to break the speed of the optical sensor and to see the transition between optic and accelerometer to make sure that this happens correctly. This is just moving the mouse. The speed here is about 250, 280 ips. It’s sufficient to break the speed of the optical sensor, but it is not sufficient to [break the accelerometer]. So we had to create another one. It has been used to validate that the mouse is the fastest in the world.