Here is what Mike says…

‘Burning Skull Overdrive.

Based on the infamous ZVex SHO.

This is a Boost / Overdrive featuring a BS170 transistor and hand wired components on a tagboard circuit. 

It has volume and gain controls that take you from boost to cranked amp overdrive.

Like the original, crackle when adjusting the gain is OK.

Power: This pedal runs on external 9v standard pedal power only.‘