I have several mags I picked up a long time ago, that are not CZ factory mags. They look suspiciously like the "CZ mfg" mags that are for sale now, but have floor plates with no markings and two weld spots identical to current CZ USA mags. I replaced the springs and followers with ones from CZ-USA and the work flawlessly (they had pretty pitiful springs in them, and the followers didn't seem quite right). I alway assumed they were some foreign contract run, or maybe from some now defunct US magazine manufacturer like National or USA Mags.