HAVE BEEN TOLD ,  THIS IS (PLEASE  CORRECT ME IF YOU KNOW DIFFERENT ) WW1 RFC FRENCH ? JAEGER Aircraft RPM Tacho R=1/2 

 IDEAL VINTAGE AERO ENGINE  , THE NEEDLE DOES MOVE ON ACCASION WITH A BATTERY DRILL BE IT DOES HAVE ISSUE'S AND WILL NEED TO BE LOOKED AT . SOLD AS SPARES OR REPAIR . 3" FACE