The NR27A became the CV1161 from 1941 and is an output triode based on the 104V.
This exhibit is labeled as a Mazda ACP but the photograph has revealed the earlier identification. The style of this earlier etched identification is in keeping with M-OV rather than Mazda. A rough guess is that Government Surplus was sold to the makers for use in the immediate post WWII period.
An attempt to see the feint image more clearly. In normal lighting the etched lettering is invisible and was found only by accident in the photograph for the ACP.
The lower mica, rectangular cathode tube with bifilar wound heater within. Above the mica can be seen the anode.
The classic envelope is 44 mm in diameter and, excluding the base pins, is 95 mm tall.
