The RAT 2 has been on professional pedalboards since the early 80s and hasn't needed much changing since. Kurt Cobain, Jeff Beck, Dave Grohl, Thom Yorke — the list is long and the reason is simple: it does distortion in a way that works on almost any amp, at almost any volume.

Three controls. Distortion dials from a pushed overdrive through to full saturation. Filter is the key — turn it clockwise to tame harsh highs, counterclockwise to let your guitar cut through a dense mix. Volume balances it against your clean signal.