I don't make a science of it. I have tried them all, Zagg, glass, regular, on different cameras. All work fine. I'm actually not a fan of Zagg, I find them to be a bit "sticky", stuff tends to dig into it. If I have the choice, I like the semi-hard plastic protectors the best. The ones where you peel off the bottom, apply it, and then peal off the top once it's on.