Autopilot Slaved Gyro Magnetic Compass, USAF E-4 System, 667258-21

This is an example of an Autopilot Slaved Gyro Magnetic Compass, Type V-3, for the USAF Autopilot Type E-4 (aka as the Sperry A-12 Gyrosyn Automatic Pilot System).  The E-4 System was used in the late 1940-1950's and was still in use in some 1960's aircraft. Lockheed C-130 Hercules and C-121 Constellation transports used this system, as well as civilian aircraft such as DC-3 and DC-6.  

The Indicator is in reasonable condition for its age.  The glass is slightly foggy but could be opened and cleaned. The case is intact. The knob rotates the compass card. Measures approximately 3.25 inches diameter and 5 inches deep.