Exhaust Gas Temperature EGT Indicator, Type K-9, F-11 Tiger
Here is an Exhaust Temperature Indicator, Type K-9, used to measure the exiting temperature of the exhaust gases of a jet engine, from 0-1,000 deg C. Made by Lewis Engineering part # 149E27 spec MIL-I-5943. The closest example in appearance was used in the 1960's US Navy jet fighter Grumman F-11 Tiger, see photo of F-11 instrument panel.
It is in fine condition given its age. The operating limits for the aircraft in which it was installed are marked in red & green tape adhered to the outside glass. Measures 2 inches diameter by ~2.5 inches deep.