The classic '70s overdrive by MXR, and is essentially the same as the DOD 250 and Ross Distortion. I designed the layout to have onboard pots, to alleviate some offboard wiring. It also has the LED resistor on the board, again to reduce offboard wiring a bit. It'll fit perfectly in a 1590B enclosure. Might be a good idea to socket the diodes. The original had germanium diodes, but silicon diodes or LEDs will sound good as well (just different).