This is a square-wave synthesizer built into a Guitar Hero guitar controller. Pushing the strummer down is a lower pitched mode and pulling up is a higher pitch mode. The five fret keys are monophonic and sound the highest key being held down, mimicking a guitar string.
This does not play traditionally tuned notes and the pitch control knob acts as a way to tune the range of frequencies laid out across the five keys.
The original whammy bar is used for pitch bending. There is a also a sort of tremolo effect that can be switched on with a large speed control. The front power indicator will then flash in sync with the effect.
There is also a switch to permanently pull up on the strummer so you free up a hand to tweak controls simultaneously. There is a volume trim control. The original power switch on back is used. It is powered by 3 AAA batteries that are accessed behind the original battery compartment. Output via 1/4″ jack.