The telephone-microphone headset "TMG-1" was supposedly produced since 1959 by the Tula factory "Octava". It was produced in two versions, with a low-impedance and a high-impedance microphone. The headset is intended for use in long-distance telephone communication equipment. Contains a carbon microphone and a telephone dynamic capsule. Line fitters also used the headset to check the line. The phone's frequency range is 300...3000 Hz. ChH unevenness 13 dB.