Welcome, you are looking at a really cool piece. This is the Pigtronix Philosopher's Rock pedal! The combination of Pigtronix's unique optical compression and switchable germanium overdrive make this pedal a necessity on any guitarist's pedal board. Their optical compressor provides clean , transparent compression that will keep your true tone. The germanium overdrive adds just the right amount of crunch to your signal. Like many other Pigtronix pedals, this pedal can work with a 9V power adaptor, but ships with an 18V adaptor for better headroom, clarity, and output! We are an authorized Pigtronix dealer! Don't pass this by!