These are extra circuit boards for a customer project for a custom Xotic EP Booster.
It uses a voltage converter to convert 9v to 18v internally so it just uses 9vDC at the DC jack. It has a internal dip switch to select a few cap for different tones. The Level control was meant for a clear shaft potentiometer with an LED up inside it. You can see this in the center of the board. You don't have to use this type of pot but you can if you want.
2 layer board of 1.95 x 1.84 inches (49.5 x 46.7 mm)
Parts List is available for download below and we will help out sourcing parts and answer any build questions if you have any.