Tachometer, Type E-13, AN-5530-1, US Navy
This is an example of the WWII-era single engine electrical tachometer, Type E-13, GE part number 8DJ13ABN. The E-13 Tachometer was used in various US fighter aircraft, such as the P-38 Lightning, P-39 Airacobra, P-47 Thunderbolt, and P-51 Mustang.
Judging from the alternating lettering color of white and Munsell green, we speculate that this particular specimen was used in aircraft of the US Navy, such as an F4F Wildcat, where this color scheme was commonly used on instruments. This example has a serial number prefix that indicates a year of manufacture of 1943.
It is in exceptional condition given its age. The glass and case are intact and the lettering is clear and precise. Measures 3.25 inches diameter and ~5 inches long.