Brutal variation of a fuzz face. FFAS fuzz is equipped with TFK BC108C high gain silicon transistors and is carefully tuned to sound as smooth and warm as a germanium one with extra gain and low frequencies available.
You have control of input gain via 'load' pot instead of 'fuzz' seen in the most FFs, what allows to have some flexibility in available amount of distortion and keep clarity in a whole range. No clean setting though - did I mention it is brutal? 'Load' knob is a handy tool to use with another pedals before FFAS, coz when turned back it 'unloads' preceding device so you can use your wah, booster or other pedals with no worries.
FFAS has also a depth pot to reduce both amount of bass and overall heaviness, which lets it turn from really bulky, beefy fuzz to somewhat lighter and cutting through fuzz with pronounced midrange.
Level knob is simply a volume control with lot of gain available so you can push your amp savagely.
Please note: to keep superfluous plastics production as low as possible, all my pedals come without battery clip unless you need it. .