Dual Pressure Indicator, Bendix, F3D Skyknight, C-121 Lockheed Constellation, S2 Tracker

This is a Dual Pressure indicator used to indicate oil pressure (left and right turbojet engines) in the US Navy's, Korean War era F3D Skyknight Fighter and hydraulic system pressure (primary and secondary hydraulics) in the US Air Force C-121 transport version of the Lockheed Constellation. It is labeled as made for the Bureau of Aeronautics (BUAER), US Navy. Also used in the Grumman S2 Tracker to indicate oil pressure.  See photo of the location of the instrument on the cockpit panel of the F3D from its manual dated 1952 and on the Flight Engineers lower instrument panel from the C-121 flight manual dated 1958. It has a inspection stamp of Oct 1982.  It is in exceptional condition and may be new old stock.Measures 2.5 inches diameter and ~6 inches deep.