This pedal is a modified version of our Box of Rock’sDistortron Engine. The improvements include a gain boost switch for added sizzle and a sub control switch with 3 levels. The amounts werecarefully selected to reduce “flubbiness” that occurs when using ampswith heavy low-end response. It would be immodest of me to suggestthat this ZVEX effect is the greatest distortion pedal of all time, but it probably is. Try it last in your chain, and beat it up withyour other effects... it stacks like a dream.