Electro-Harmonix is one of the very oldest brands in the effects buisiness today. I can remember first seeing their stuff in the very early seventies. I think the first thing they came out with was the LPB. The Big Muff is one of the most copied pedals on the planet... clones and variations on it's circuit have been around for years. The big deal with 'em is that up untill recently, most of their pedals have been analog. It's generally accepted that analog pedals sound better than digital ones, so the older E-H pedals are highly prized.