Airspeed Indicator, 500MPH, Army Type D-7, US Army Air Force, WWII
The Army Type D-7 Airspeed Indicator was used across a number of US Army Air Corps and Air Force aircraft during WWII, including heavy bombers B-17, B-24, B-29, medium bombers B-25 and B-26, as well as light bomber A-20, according to the Accessories Interchangeability Chart dated Feb 1945. It was also used in versions of US Army Air Force WWII fighters P-38, P-39, P-40, P-47, and P-51. This D-7 was made by Kollsman, part number 586BK-028, and has a serial number prefix of AF43, indicative of a 1943 manufacturing date.
According to the spec sheet in the Index of Army Aeronautical equipment Volume 6 Instruments, dated 1944, the D-7 Airspeed Indicator is a differential pressure measuring instrument used to indicate the speed of the airplane through the air. The dial face contains graduations from 50 to 500 miles per hour; the graduations from 50 to 200 m.p.h. are open scale marking, and those from 200 to 500 are condensed scale markings.
It is in exceptional condition given its age. Just needs a bit of cleaning.