Zvex Mastotron Silicon Fuzz Guitar Effects Pedal (FBA-MAST)A sub heavy silicon fuzz with some new twists: An input impedance control (push relax) that adjusts from passive pickupsto line level. It works very well for re amping bass tracks that needto be fuzzed up after tracking and keyboards. Theres also a three position sub control switch, a treble tone control, adjustable pulse width, and a wide fuzz depth control. More flexible than any silicon fuzz to date. Pedal Dimensions (LxWxH): 4. 70" x 2. 38" x 1.