Welcome, you are looking at a great piece.This is the Maxon OD-9 Pro Plus Overdrive Electric Guitar Effect Pedal.The Nine Series Overdrive Pro+ takes Maxon’s classic OD-9 circuit and serves it up with two side orders of Whoop-Ass in the form of 9/18 volt operation and a Mid Boost switch.In 9-volt setting the Pro+ sounds and functions like the standard OD-9 with the added option of a healthy +3 dB of midrange boost at approximately 800 Hz (actual frequency is dependent on Control settings)– great for cutting through a band during solos.When set to 18-volts the OD-9 Pro+ becomes an 800-pound Gorilla, offering up beefier lows, tighter saturation, improved dynamics and a chunky, aggressive pick attack that will make your amp sound and feel like it just took a Viagra. Switch on the Mid Boost in this mode and let your solos breathe fire.Don’t just play like the pros – play with the Pro Plus.We are an authorized Maxon dealer.Don’t pass this by!