The note is - the CZ +2 bases CZ USA sells with the CZ logo on the bottom are not the same as the +2 bases that say Mecgar on the bottom.
Both work on CZ magazines though.
The ones that say Mecgar on the bottom also work on my M&P 17 round magazines to make the 19 round magazines.
The ones that say CZ on the bottom will go on the M&P magazines and you can put 19 rounds in the magazine - but they will not lock into the mag. well of the pistol.
The plastic, above the slot that slides onto the flange of the bottom of the magazines is thicker on the magazines marked with the CZ logo.
Yes, ran into that yesterday and fixed it by swapping Mecgar bases off CZ magazines to M&P magazines and putting the new CZ bases on the CZ magazines.
This stuff seems to happen to me for some reason.