Ammeter, 250mA, WWII Japanese Navy Aircraft

This is a Japanese Ammeter, 250mA.  It is presumed to be a WWII-era indicator used in aircraft of the Japanese Navy, judging from the anchor symbol on the lower left of the dial. This has not been verified.  Aircraft that may have used this have not yet been identified.

It is in good condition given its age.  Measures 2.5 inches diameter and ~1.5 inches deep. The glass and case are intact and the lettering is distinct.