This is the headset of the R-392 man pack radio. It uses a dynamic microphone, as well as a dynamic speaker. This is a typical setup for army radios, since dynamic microphones are more resistant then capacitor or piezo based ones.
However most amateur radios only work with those. So I had put in a piezo microphone, in order to get this thing running with my Wouxun KG-UV6D. The speaker is good to go without any modification.
(photos taken from: armyradio.com)
The R-392 radio, which this headset belongs to, was developed in the 1980’s and can be still found in service. It offers 6 fixed frequencies: 44.3, 44.6,44.9, 45.2, 45.8 MHz. The design of the device itself is pretty similar to its predecessor – the R 126.
The radio is carried on the back and often used in the role of a patrol radio.