This is an N2 indicator guage as removed from the BAe125 aircraft. The unit is in very good condition, and is used to monitor engine data (Percent RPM) by the flight crew.
The rear cannon plug appears in good order and the seals and data plates are present.
An ideal addition for a variety of flight simulators. Could you converted to functional with the correct knowledge or rewiring the unit. Alternatively would make an ideal display piece.