This is a five key square-wave synthesizer with sweeping LFO (low frequency oscillator) modulation. There is a frequency control that sets the range of pitches laid out on the buttons, so it does not play specific traditional notes. It is monophonic and will sound the highest pitch being played.
The sweeping LFO modulator can be turned on or off with a second switch and has a control for speed. A green LED pulsates in time. This is an analog circuit and often makes a slight click when it sits idle at low speeds. Also the effect lowers the volume slightly but can easily be adjusted with the volume control.
There is a power on/off switch with a green LED and a 1/4″ output on the face. Power is supplied by wall adapter.