Optics have been a hobby of mine for many years. I have had many sets of glasses both commercial and military besides assembling my own.
I have owned about 5 or 6 of those units you mentioned.
I bought 5 sets one time to get the best optics from the best "one." Their coatings were not matched to well and you could get different colored lens coatings on the SAME unit.
They were/are made in China as a copy of the old Zeiss. They certainly are not Zeiss quality but they are not too bad for viewing.
They had the 25X and the 40X eyepieces on a turret and had 100 MM objectives.
The unit is very heavy and they do come with a wooden tripod like the surveyors use.
11971,
Now the Kowas are a different critter. You put a set of them babies together and you'll have something. I always wanted to do it but waste too much money building new rifles.LOL