The project began as a compact take on the discontinued Gray Channel, which Kiernan used as his main drive. The overdrive side is based on that pedal's green channel, with its clipping diodes removed. Go sets the drive, from full-range clean boost to op-amp distortion, and That's It sets its volume.

On the fuzz side, the signal becomes a square wave whose pulse width follows pick attack. With Yes! fully down, the fuzz sustains and goes silent when playing stops. Turning Yes! up narrows the pulse width on hard notes, thinning the tone until it cuts out and swells back. Oosh sets the fuzz volume.

Each side has its own footswitch, and both can run together. A TRS expression pedal can take over the Yes! sensitivity. Because the envelope reacts to input level, pickups and pedals placed before Gary change how the fuzz behaves.