This is the pointing receiver of the MAJÁK setup (newer version), intended to receive and pinpoint the signals form the bunker collapse transmitter. The operating frequency is 96kHz, at which the receiver produces about a 1kHz beat signal. The sensitivity is very good, receiver has a plastic-only, but relatively rugged construction.
For a longer operation, there is a container for 3pc. of 3F12 "flat" batteries available. The whole MAJÁK setup was developed and produced since 1970 a TESLA Pardubice and, surprisingly, it was a part of the Czech Civil defense equipment till the nineties. This receiver version is from about eighties of last century.
The receiver in my collection is in a 1A shape, no damages, unfortunately no accessories, nor packaging, documentation.