Keeley Synth-1 Reverse Attack Fuzz Generator Effect Pedal w/Box - UsedThe Keeley Synth 1 is a guitar triggered, single note wave generator. Use the Filter and Blend controls to mix your guitar with the fuzz from the synth. The lead in time or swell of the note is controlled with the Attack knob. Then use the Blend control to remove the natural tone from your guitar as you slide through synth sounding fuzz waves. Use an expression pedal to control the Filter, and now you have wah like control of the Synth 1. Excellent