This is based on the stepped tone generator designed by Forest Mims, also known as the atari punk console.
You have controls for frequency and pulse length as well as a volume control, toggle on/off, and a neat power indicator light on the side. It runs off an included 9v battery. A standard 1/4 inch jack makes it perfect for connecting to amps or recording equipment.
Hand-made with many salvaged components, this hits slightly less piercing frequencies then some similar devices. When played this can create some interesting sounds.