50 built in audio effects or sound generator patches that you manipulate by moving your hand in the air over the AirFx device in x, y and z axis. One physical knob controls patch selection and lets you 'freeze' the location of your other hand or bypass the effect. To the best of my recollection I am the only owner of this thing. It is in excellent condition with one notable ding in the blue plastic, as pictured. I recently bought this replacement ac adapter as I had misplaced the original adapter.