Got this from the local small ads today
Voltcraft Dosimeter - Radiometer (re-branded Russian made RKSB 104)
Overall it seems to be in good shape, fully working, including the original case and manual.
Hopefully I can dig up an old contact to check how far of the calibration is.
The device can measure the dose equivalent rate of gamma and beta particles in µSv/h. There are two measuring periods to select from (27-29 seconds and 270-280 seconds). The longer period is for more accurate readings. Besides the measuring mode there is also a surveillance mode with configurable alert threshold.
Since I did not find any information on the device here on the forums, expect tear down pictures and some more in-depth information coming soon
Edit: I posted the name in cyrillic unicode, but the forum software can not handle that - very disappointing. Did recognize the lack of supported chars before (accents et.al.). meh