Another gauge corrector--cheaper than MeterMatch, 33.00

The 5 black things at the top are tactile switches, yes. The blue box at the bottom is the potentiometer which according to the instructions is used to adjust all ranges. Select the range, adjust the pot until gauge reads correct than save the setting. Repeat for all ranges. So its not manual but not a "computer program" either. Its just saving values for each range. It just adds or pulls resistance from whatever the sending unit is reading at a certain range.
Its impossible to know exactly how it works without seeing a schematic or at least knowing what chip is on board.