Someone say Brno ZKK

The QD factory mounts came in three different models to suit the three different ZKK action lengths:

ZKK601 Short (.223/.243/.308 etc)
ZKK600 Medium (7x57mm/.270/.30-06 etc)
ZKK602 Magnum (.375H&H/.458 etc)

They are clearly stamped on the left hand side rail as to what model ZKK they fit.

There was a range of Zeiss Jena scopes available not all have machined lugs or a boss to fit the ZKK mount. Some were set up to suit drillings and have a different lower mount block configuration.

It would be far better to get an original ZKK factory scope and mount together.

4x32mm (most common size on ZKK601) or a 6x32mm (more rare, most I've seen are on ZKK600 mounts).
You can swap the ZKK type Zeiss Jena scopes over between ZKK mounts easily.

They turn up on eBay from time to time and seem to go for around $300-$400 if in good condition with original leather caps. I was watching a ZKK600 4x32 that just finished a few days ago...

Even more rare are Brno ZKK QD mounts that have been modified to fit 1" standard scope rings... Ausinel in Australia offered them as a standard line many years ago. I also picked up a set in Europe on eBay... they are around if you look hard.

Hope this helps...