Hi John, see the CZ Magazines Compatibility Guide here >>> cz-parts.com/cz-magazines-compatibility-guide
Stay safe & have a great day!

All polymer magazines *technically* fit each other unless the magazine is too short. | *exception is CZ P-10M as it is the only polymer CZ that is using single stack magazine*
The mags differ from each other in two aspects: length and mag pads.
length - you will get P-09 magazine into P-07 and it will work, but the magazine is longer so it will exceed the grip
mag pads - you can use P-10C magazine in CZ P-07 - the length of those mags will be the same - but CZ P-10C has thicker frame and thus uses thicker mag pads than CZ P-07 - if you then use CZ P-10C mags in CZ P-07, it can feel uncomfortable in your hand as it can interfere with the grip
The length difference is quite simple - if you use magazine from larger polymer CZ in smaller polymer CZ, it will work but the magazine will exceed. Of course you cannot use it the other way - magazine from smaller CZ cannot be used in larger CZ as it will simply not get deep enough. cz-parts.com/cz-magazines-compatibility-guide

Hi John and welcome. CZ 75 Compact, 15-round P-10 C, and 17-round P-10 C mags. All seated, fed, and locked open. Details here: reddit.com/r/CZFirearms/comments/1ex4gfe/for_anyone_curious_p09_c_nocturne_mag_fitment/