Airspeed / Mach Speed Indicator, Type AVU-8-B/A
This is a 1960-70's-era combination Airspeed and Mach Number indicator with Maximum Allowable Speed indicator, US Air Force Type AVU-8-B/A, made by Aerosonic, part number S85-AVU-8-B/A. Small "USAF" initials appear on the face below center. The AVU-8 or -8/A was used in early versions of the US Air Force's F-5 Freedom Fighter and T-38 Talon Trainer, and the A-7D Corsair II Attack aircraft. See image of the A-7D instrument panel from its flight manual showing the location of this instrument.
The range of the indicator is from 80-850 knots and 0.5-2.2 mach. A white airspeed index marker (seen between 550-600 knots in the photos) can be set by rotating the small knob at the lower right corner. On the back is an adjustment screw for setting the maximum allowable speed marker. By removing the larger cover screw, the adjustment screw is revealed beneath. Turning this screw sets the red index marker on the dial (set at 700 Knots in the photo displayed here).
There is an interesting video showing the AVU-8 in bench test operation here.
The indicator is in very good condition. The beige seal beneath the glass is slightly dislocated (see photo), but could probably be corrected.Measures 3.25 inches square and 6.25 inches deep.