Oxygen Flow Indicator, MK III, British Royal Air Force, 1942 A-26 This tachometer has a serial

This tachometer has a serial number prefix of AC 41

Type 98 Reconnaissance Seaplane Aichi E11A Laura

not surprisingly

It is presumed to be a WWII-era indicator used in aircraft of the Japanese Navy judging from the anchor symbol on its face (lower left

Oxygen Flow Indicator, MK III, British Royal Air Force, 1942 A-26 This tachometer has a serialHere is a WWII era artifact: an Oxygen Flow Indicator, Mk III, Stores Reference 6D 430. Multi crew RAF aircraft had these installed at crew stations, such as gun turrets, radio operator, navigator, etc., to indicate the gross flow (not the precise rate) of oxygen from the primary oxygen tanks (not portables) to the local junction at each station. Commonly used in aircraft such as the Lancaster, Wellington, Stirling, Mosquito, etc. The serial number on