Ammeter, 600mA, WWII Japanese Aircraft

This is a Japanese Ammeter, 600mA.  It is presumed to be a WWII-era indicator used in aircraft of the Japanese Army or Navy. This has not been verified.  Aircraft that may have used this have not yet been identified.

It is in good condition given its age.  The case is intact and the lettering is distinct. The glass appears to have two layers and there is a bit of separation between the layers in the bottom half. Measures ~2.25 diameter and ~1.5 inches deep.