A 6072AM vacuum tube, microphone tested, for replacement in 22 47, 22 251*, P-12 microphone. Also, for a limited time we produced our P-248, this microphone also uses the 6072AM Vacuum tube.  Please note, the M at the end of the tube id number denotes the tube as been tested for microphone. (6072A vs 6072AM)

Please note, some model 22 251 microphone implement a 5744 WB sub-miniature soldered in tube.