Works great with the CZ 5 round poly mags, but foul on the 10 round steel mags making them impossible to remove. No experience with the 10 round poly's as they've been sold out here for 18 months.
A couple pairs of pliers and a little bending the lower portion forward, they work fine with the steel mags but not the prettiest solution.
Great product otherwise, but be aware of the above.