Darkglass Duality Fuzz Bass Fuzz Pedal w/ 9V Power Supply Blend: Mixes the clean with the fuzz signal. The clean signal remains at unity gain while the volume of the processed one is set by the Level knob, allowingfor fine control of the blend ratio. Duality: Selects and mixes the fuzz circuits. Set it counter clock wise for the old school saw-tooth shaping circuit, turn it fully clock wise for the modern, high gain one Filter: Use this variable LPF (low pass filter) to cut or bring up the high harmonic content. Great for fine tuning the perfect amount of presence and edge. Level: Sets the output volume of the affected signal.