Up for sale is this Keeley Neutrino Envelope Filter! This is an amazing compact envelope filter with a super simple layout to give you complete control over your sound. You get 3 knobs, one for the filter sweep ( Low Pass, Bandpass, High Pass), a Gain knob and Peak knob with a selectable range (Hi/Lo). You get some incredible funky filtered vocal-like tones from this great pedal. This pedal is in good condition.