Four Engine Tachometer Panel Segment OV-1 The manual covers instruments that

The manual covers instruments that were eventually used in aircraft of the Air Corps US Army and Air Force US Army during WWII

The problem with using this indicator was not only identifying the aircraft

or "Pocket" Sextant

The case measures ~11 inches by ~8 inches by ~18 inches

AN 01-190EB-1

Four Engine Tachometer Panel Segment OV-1 The manual covers instruments thatThis segment of a reproduction cockpit instrument panel contains two dual engine tachometers, both made by Kollsman (Type 740CK), a dual temperature gauge (AN5795T6A) made by Electric Autolite, and a red warning lamp. We have not identified what aircraft may have used the tachometer, but the dual temperature gauge was commonly used in aircraft of the US Army Air Force and US Navy. The tachometer pointers are labeled for Engines 1 & 2 and 3 & 4.