Engine Gauge Unit (Triple), AN5774-8
The WWII-era Engine Gauge Unit (aka Triple Gauge), AN5774-8, displayed the performance of 3 engine parameters in one instrument: Oil Temperature, Oil Pressure, and Fuel Pressure. The AN5774-8 unit was used in the US Army Air Force fighters P-38E Lightning, P-40 Warhawk, P-47 Thunderbolt, and P-51 Mustang according to their Maintenance Interchangeability Chart dated Feb 1945, as well as having been used in other military aircraft post-war.
This instrument is in reasonable condition for its age. This particular instrument has a stamp of the US Navy, so it was likely used in a USN aircraft. Measures 3.25 inches diameter and ~3 inches deep.