New here, thanks for the link to GC! Saved me some $$$! Had some questions and Greg picked up the phone, after hours, and helped me. That's customer service!
Ordered some Mec Gar CZ-75ZB, .40, 10-rounders. Wanted to know if the factory rubber bases would work. Apparently not on the .40, 10-round, Mec Gars, as their base plates are polymer(?) vs. the factory steel. Greg actually took time to try test fitting them, and they don't quite fit. If you want the rubber bases, get the factory mags.
The 9mm, and higher cap .40, Mec Gars apparently DO have metal bases, like the factory mags, so they might work. I had called, because my particular situation wasn't mentioned in Greg's site description. So, when you hear that the factory and Mec Gars are the same, there may be some exceptions.