Attitude Indicator, Type ARU-11/A, USAF F4 Phantom II
This is a Cold War / Vietnam War era Attitude Indicator type ARU-11/A, made by Lear, Model 4060P, part number 139001-01-04, MIL-I-27610. This instrument appeared on the pilot's instrument panel of the US Air Force F4 Phantom II jet fighter. This unit has a service label from McClellan Air Force Base in Sacramento CA dated 1984.
The purpose of the instrument is to rapidly indicate to the pilot the attitude, or relationship, of the aircraft with respect to horizon, showing whether the aircraft is climbing, diving, or banking left or right, and to what degree. This model also has a small floating-ball turn/bank indicator at the bottom of the instrument.
The instrument is 'experienced' but still shows well. The unit requires the correct electrical input in order for the knob and sphere to function. Measures 5 inches square and ~8.5 inches deep.