The ProCo RAT ranks as one of the most widely used distortion pedals ever, a favorite of such disparate musicians as Jonny Greenwood, Nels Cline, Kurt Cobain and John Scofield. The ProCo RAT 2 emerged in 1988 and continues to be a popular pedalboard staple for both guitarists and bass players with its characteristic jagged gristle, courtesy of the legendary LM308 chip.