Before I get confused MORE than normal, current 9mm CZ mags are made by Mec-Gar. The Mec-Gar "aftermarket" CZ mags are slightly different than the OEM CZ mags, including the follower and bases for the 16rd magazines. Mec-Gar doesn't offer an 18 rd magazine--just a 17 with an extended base.
CZ USA carries "CZ magazine followers". I have purchased those some time back, and they do fit OEM mags.. I don't believe these will fit current Mec-Gar aftermarket CZ magazines.
Confused yet? 
Just to clarify for anyone curious about this, there are three basic OEM styles (to my knowledge):
1) First version of the "Czech" magazines. (For all I know, these could have been made in Timbuktu, but everyone has always assumed they were made in Czechoslovakia!) These are the smallest of all, and they were apparently the standard from 1976-1980. I have never seen a "short rail" CZ 75 in person, but in all of the photos I've seen, these magazines have the serial # of the pistol stamped or etched into the magazine body. As you might expect, finding these magazines is virtually impossible. Apparently, the farther back you go, the less likely you are to find magazines that fit that particular pistol, except the ones issued with the pistol. I have no idea what the followers look like.
2) Second version of the "Czech" magazines. These seem to have been more or less the same from 1980 to whenever CZ-UB switched to Mec-Gar. I'm not sure when the switch occurred, because the Crime Bill sort of clouded the issue. The OEM magazines from my '82, '86, and '93 CZ 75s are dimensionally and functionally identical. These were imported by CZ-USA in fairly large quantities in order to be "grandfathered" and therefore legal under the Crime Bill. I was able to buy quite a few from CZ-USA as late as 2001. These have a relatively poor follower design that I have always called the "tab-n-slab." (See photos below.)
3) The OEM Mec-Gar magazines. Other than the 97B and P-01(?), I've never owned a CZ that had these as OEM. The 10 round magazines that came with my other pistols were obviously altered Czech magazines.
There was a period in which Mec-Gar made aftermarket magazines for CZs, but they weren't the OEM supplier yet. I have no idea for how long. In 2001-2002, a CZF member sold these to members only. I don't recall the details, but he was able to get a large quantity of these that had been imported and "grandfathered" before the Crime Bill deadline.
These are slightly different from any other Mec-Gar magazines I have seen since. These are the only full-size 75/85 series Mec-Gar magazines I own. (See photos below.) These magazines do NOT hold 16 9mm cartridges, even when the springs are older/weaker. All of the "witness" holes are on the right side. All of the markings, which are quite numerous, are on the left side. These have a large marking "- A -" near the top of the magazine body. Supposedly, this is "- A -" for "Aftermarket," but I have no idea. These particular magazines tend to fit the later Type A CZs, so I guess it's remotely possible the "- A -" is for "Type A." They have a stepped base, FWIW.
At any rate, I discovered that if you used the Mec-Gar follower from these magazines with the later Czech magazine bodies, they will reliably hold and function with 16 9mm cartridges. I've never had any problems with the Czech followers, but they seem to be less stable than the "four leg" design used by Mec-Gar.
As per usual, I must apologize for the poor quality of the iPhone photos...
These are the followers I was mentioning. The Czech "tab-n-slab" is on the left; the Mec-Gar is on the right.
These are the "left" sides of the magazines. Czech is on the left; Mec-Gar is on the right. You can't really see the markings. The Mec-Gar logo is in the center. There is an "- A -" high up on the body. Near the base plate there is the following marking "MG - CZ75 - 9MM."
These are the "right" sides of the magazines. Czech is on the left; Mec-Gar is on the right.
