The compact Boss AC-3 is a guitar effect pedal that allows you to strum authentic acoustic tunes on your favorite electric guitar. Using the latest COSM technology, the Boss Acoustic Simulator can reproduce the sound of a variety of quality acoustic guitars. This guitar effect pedal includes simulations of standard (regular acoustic), jumbo (large bodied acoustic), enhanced (responsive acoustic), and Piezo (acoustic with piezo pickup) guitars. The Boss Acoustic Simulator includes controls for harmony (top knob) and resonance (body knob). The Boss AC-3 includes built-in digital delay fashioned for acoustic sound. Powered by the PSA series adapters, this guitar effects pedal provides every guitarist with great performance flexibility.