If it’s a two knob version, the one on the left is essentially a gain & the one on the right is output volume.
Current builds have two separate outputs. The outermost is connected to the true bypass circuitry, while the inner output is nested within circuitry – this results in the inner output being turned off when the effect is bypassed.
The inner output and banana jack (if installed) will tolerate DC bias from a following stage without reflecting that onto the primary output.
Early units can have levels dialed completely down.
Contains diode protected negative center power supply, keep it under 24 volts.