Sustain moves the fuzz from mild crunch to heavy saturation. Filter sets the range of the band-pass filtering applied to the fuzz. Loudness sets the output level relative to the bypassed signal, so the fuzz can be matched to the rest of the chain.

Scoop sweeps the mid frequencies between the classic scooped shape and a flat response. Crunch alters how strongly the fuzz compresses. Two more controls sit inside the enclosure. Voice sets how deep the Scoop cut goes. Clip selects between two sets of clipping diodes.