The guys at iFixIt
explain that, originally, the iPhone 4 shipped with standard, albeit very small, phillips screws in its base. Removing those two screws meant easy access to the phone’s innards. Now though, Apple is switching to a completely unique screw, with rounded inside edges, dubbed the “Pentalobular Screw”.
Those new screws are standard in freshly manufactured iPhones, and if you take your iPhone in for a repair iFixIt says Apple’s engineers will actually swap any phillips screws for the new, high security versions.
“This screw head is new to us,” says iFixIt. “In fact, there isn’t a single reputable supplier that sells exactly the same screwdrivers Apple’s technicians use—which is Apple’s point. They picked an obscure head that no one would have.”
The screw continues Apple’s policy of locking down its products and deterring hackers, modders and homebrew fixers. You can find the iFixIt iPhone 4 Liberation Kit for $9.95 here