The Pro Co Rat is a distortion pedal that was popular in the 1980s and early 1990s. Many guitarists used it to get a gritty, overdriven sound. Some of the most famous users include Eddie Van Halen, Kurt Cobain, and John Frusciante. The Rat has been through several iterations over the years, but the basic design remains the same. It features a simple three-knob layout with controls for volume, distortion, and filter. The pedal can be powered by either a 9V battery or an AC adapter. Despite its age, the Pro Co Rat is still widely available and relatively affordable. It continues to be popular among guitarists who appreciate its simple design and rugged construction.