I had a Zagg full coverage shield on my iPhone 4 and then bought an Otterbox Defender. It fit fine but I did not like the poor interaction between the Zagg covered face and the face shield on the Defender. It left watermarks all the time despite the Baby Powder treatment. So... I just, carefully, removed the built in shield from the Defender. Now I have the best of both worlds. Full Zagg coverage plus the unbeatable protection of the Otterbox.