The Alexander Pedals Litho Boost is based on the classic Pharaoh Class-A boost pedal.
In fact, Alexander is so forthcoming with this fact that it admits the Litho is a direct copy of the Class A. It is that good.
As for the three controls, we have the ubiquitous Volume and Tone controls but the bread and butter of the Litho Boost is the Contour knob, which changes the character of the boost from chimey and transparent to fat, gritty and powerful.
Part-for-part recreation of the Pharaoh Class-A boost
Contour knob changes the transparency of the boost
Standard 9v center-negative operation