The Dresden Synth Fuzz is a quite unique pedal. Combining two synthy-sounding octave fuzzes run in parallel - an upper and lower octave fuzz - it covers the whole frequency range. It's dirty and snarly on the low notes, almost like a malfunctioning analogue synth, and relentlessly precise on the higher notes. It is always rewardingly noisy!
The big synth knob is simply the volume control. The small switch in the upper left selects either the upper or lower octave fuzzes or both of them combined.