The Pigtronix Resotron is a synth filter pedal that is activated not only by the dynamics of your playing, but also tracks based on your pitch. There are options for the envelope filter to be applied to your high or low frequencies, and you can select between an envelope up, envelope down, or pitch filtering. The result is a vintage synth sound that works for guitar, bass, and more. This pedal itself is in excellent condition. It comes with its original box and 18v power supply