Apologies for writing in English but ich nicht spreche deutsch.

These appear to be the same model slightly modified as the Australian Army's Vietnam-era 6x30s that periodically pop up on eBay Australia. The Army are still disposing of them in small quantities but I suspect most of them had a hard life and I wouldn't buy one without close inspection. Actually at 6x30 and individual focussing eyepieces I don't have a use for them at all.

There are some good photos here
[www.miniaturebinoculars.com]
and scroll down.

Ignore his labelling of them as made by Nippon Kogaku (Nikon). One photo shows the manufacturer's code J-B2 which is of course Katsuma.