Suction Gage, AN 5771-5, US Army Air Force WWII C-47 It has a service label

It has a service label from the US Air Force Tinker Air Base's OCAMA (Oklahoma City Air Materiel Area)

It is a hand held finder used to ascertain the range of an enemy aircraft based upon its known wingspan

very similar to AS-27A of the ARN-5 system used in bomber and transport aircraft of the US Army Air Force

the difference between the totals is the difference in density of the two fuel types

Its face has embossed "BU AERO USN" i

Suction Gage, AN 5771-5, US Army Air Force WWII C-47 It has a service labelThis is a WWII era Suction Gage, AN 5771 5, made by Collens. This indicator has a serial number prefix "AF 43", evidence of a manufacturing year 1943. The AN 5771 5 Suction Gage was used across all aircraft of the US Army Air Corps, including bombers B 17, B 24, B 25, fighters P 38, P 40, P 47, P 51, and transport C 47. The Suction Gage measured the amount of vacuum generated to power the pneumatically operated gyroscopic instruments, such as the Gyro