I have no idea. Maybe in Czechoslovakia there is some demand for 2-5/8 (67 mm) shells.
I have put multiple cases through my shotgun this year and they seem to be good quality and also cheap enough.
All based on cost and availability this year I tried a can of federal XM127 which seemed good, and also a case of federal estate (which was some white box made in France) and it was really dirty to clean the gun afterwards. I'd buy another case if my cabinet wasn't full right now.