This is the Transmission Killer dual effect pedal. See the pictures in the manual linked below for some suggested settings and available sounds.
OVERDRIVE / DISTORTION On the right hand side is an overdrive/distortion/fuzz circuit, which I originally built as a rhythm distortion for my board. It goes from very gentle breakup to chunky, full-range distortion with a variety of articulate tones available in the sweep of the Gain knob. Pulling the Vintage/Modern knob to the left will roll back the bite of the overdrive to a smooth classic rock tone, while pushing it to the right will give you more of a punchy, in-your-face distortion.
Engaging the 'kill' switch (i.e. putting it in the DOWN position) adds in an extra discrete amplifier and clipping stage, completely changing the sound. In this mode, the Gain knob allows for heavier distortion and fuzz sounds. The tone knob becomes more of a treble rolloff and the Vintage/Modern knob operates roughly as normal. This mode started life as a circuit bend for my personal prototype to get a more extreme distortion, but I liked it so much I left it in as a bonus option.
PREAMP On the left hand side is a discrete preamp and treble booster circuit that started life as a modified Space Echo preamp, based on the circuit found in vintage tape echos. There's an option to make it a clipping circuit using an internal dip switch, and there's also a trimmer internally to control the treble boost. With the clipping ON, the preamp volume on the outside of the pedal doubles as a Gain knob for the level of clipping. The setting it will ship with is a light treble boost. This is a loud preamp, so start at 12 o' clock and work upwards from there.
You can download the manual for the Transmission Killer here.