Original U.S. Vietnam War Hand Held AN/PRT-4A Radio Transmitter Spanish Military Equipment From the data plate visible

From the data plate visible on the inside of this unit

and is marked on both the top of the barrel and the lock (faint) by the maker:

At about the same time

the British version of the famous German BLÜCHERSÄBEL (Blucher Saber)

and those integrated with French units were given French M15 Adrian helmets

Original U.S. Vietnam War Hand Held AN/PRT-4A Radio Transmitter Spanish Military Equipment From the data plate visibleOriginal Items: Only One Available. Introduced in 1965, the PRT 4A is a 2 channel crystal controlled handheld FM transmitter, for use with helmet receivers as part of a set. The A version transmits a 150 Hz tone that opens the squelch on receivers so equipped, such as the VRC 12 series, the PRR 9 (XE 9),and PRC 25 77. Power output is 450mW on Channel 1 and 50 250mW on Channel 2. The radio has an empty skeleton detachable bottom BA 399 U battery