One, new in box, RCA USN CRC 5R4GY, military issue tube. USN is US Navy. Black plates, hanging filament supports, with the lower silvering, dual D-getter, brown micanol base. Tested on a Hickok TV-3 military tester that has been calibrated, just to make sure. Firm base, excellent silvering. The tubes tests at 166-165, where pass/fail is 80. These are relative numbers and do not indicate percentages.  Tube has the date code of "K5E", September-October 1943.  If you don't have the budget for a Western Electric 274B tube, these are the closest practical tubes you can come to that. A