The 4 Knob Fuzz is now the 5 Knob Fuzz. The only difference is the internal Trim pot has been moved to the outside of the pedal.
Based on the original Fuzz pedals from the late sixties, the 5 Knob Fuzz is a Germanium based fuzz pedal that has quite a few more options than its mentor. With a few added options that will help you shape and tune your fuzz sound to the one of your liking. Along with the original Germanium Fuzz Face sound you now will also have a few extra controls at your fingertips. Among them are, Volume, Shape, Fuzz, Bias and Tones.
It should also be noted that the 5 Knob Fuzz works off of a positive ground. What this means is if you are using a power supply it has to be a dedicated 9v power supply. The pedal will not work with multiple power supply set ups such as a DC brick ect...