A synthesizer controlled by light and shadow using your hand over the photocell (the red lens). Control pitch, frequency and volume. Includes a volume control knob, on-off switch, green LED indicator light and 1/4" instrument out jack. Operates on one 9 Volt battery, included. Awesome spacey, sci-fi sounds. This thing can get very loud and has a great range from extreme high frequencies to very low rumbles.