It's oddball because the meter's zero is at 1/4 scale. You might be able to move it back with the zero adj. screw.
sanwai J0408 panel meter and two resistors, inside.
3V FSD the meter coil is 100R and 2k9 resistor, for 3k total and 1mA gives 75% deflection.
15V FSD 100R meter and 12k (between 3V-15V jack) plus the 3V resistor for 15k total.
I can't remember all the DIN 16257 symbols on the panel meter faceplate:
Horseshoe = DC (no rectifier diodes inside)
< = inclined mounting 60 degrees.
star = ? I think it's classroom grade, not measurement grade.
2.5 = accuracy class 2.5% of full-scale