It is kind of infuriating for me that there are 16, 17, 18, and 19 round mags available for the CZ75.
The 16 round mags with rubber base pads are far and away my favorite mags for IDPA and Production. They also work with the CZC basepads to get to the 140mm length and can hold 20 with the stock springs and followers and up to 23 with the Grams Springs and followers. They will not work with .40 S&W. These will fit in either box.
The 17 round Mecgar AFC mags are also excellent although I don't care for the plastic basepad. They will fit 12 rounds of .40 S&W without issue. These will fit in either box.
The 18 round SP01 Factory Mags need a much stronger spring to work properly and it seems like kind of a waste to me to spend $35 to add 3 rounds with a baseplate to get to 140mm. They are also much more expensive than the other options.
The 19 round Mecgar AFC mags (+2) are also excellent and are the easiest ones to take apart for cleaning. They will fit 14 rounds of .40 S&W and maybe one more if you trim the follower. This will definately not fit in the IDPA box.
I have not broken any of these mags over the years but I have cracked some followers and worn out a few springs. I wish my 1911 mags were this tough.