Synchroscope Kollsman 549N-06 PBY Catalina 2
This is an authentic WW2 vintage Dual Engine Synchroscope Indicator made by Kollsman, PN 549N-06, as used in the WW2-era US Navy's Consolidated PBY Catalina Patrol Bomber / Seaplane (see photo of PBY Instrument Panel from the Pilots Flight Manual with a yellow dot showing instrument location). The US Navy Anchor logo is stamped on the back and on the face is embossed "BU AERO US NAVY" (Bureau of Aeronautics). A synchroscope informed the pilot or flight engineer whether or not a pair of engines are turning at the same RPM's, i.e. are synchronized.