Featured in this page from the Jimmy Ellis fansite Orion.

This Altec 195a microphone with 29b capsule and power supply was worn by Elvis while recording in the studio/rehearsal and also live. It was bought from Elvis record producer/ sound engineer Pill Porter in the summer of 1973 by veteran producer/chief mastering engineer Chet Bennet who has worked at CBS, Columbia Records and others. He owned the mic until March, 2014 when I bought it from him (see letter of authentecy [sic]).

The mic is identical to the one that Elvis wore on his legendary 1968 Comeback Special on NBC. I have asked the producer of the show, Steve Binder and also the sound engineer, Bones Howe, who both said that the equipment they used on the comeback show was delivered by NBC at their request. Where Elvis’ mic is now today is not known but if by any chance NBC leased the equipment from Bill Porter (who had already worked a lot with Elvis) then this might be the actual one.

It still works and sounds great.

You will find an interview with Bill Porter where he mentions the Altec mic here.

The letter of authenticity can be viewed here and reads:

Mr. Kenneth Dokkeburg, this letter is to reference the Altec model 195a microphone with the 29b capsule and its power supply. The microphone was bought from record producer / sound engineer Bill Porter in the summer of 1973 when I went to his Las Vegas studio [United Recording] to purchase used recording equipment for my Florida studio [Titan Sound Studios]. At this time I noticed 2 Altec microphones and I asked Bill about the mics as I saw the same Altecs with Elvis using them. He said he owned two of these mics, one was used for rehearsals and the other one for Elvis to use in his Las Vegas concerts and shows which Bill did the sound for. The mics fell out of favor and were later replaced with another brand. The Altecs were put in storage on a shelf. I bought the mic that was used for the Elvis shows not as a collector but as a working studio mic. Regards, Chet Bennett Divide, Colorado USA