Changing the back glass cover of your iPhone 4 isn't as hard as you would think, in fact it's as easy as putting on an Apple Bumper case. All you need to do in order to replace the back glass housing of your iPhone 4 is to simply remove the two little screws located in between the speaker and mic, and then you just slide the back cover upwards a bit and your done. These metal back covers are extremely cheap at $13 and would be a great idea to have instead of having to worry about glass shattering. Wired reports that this will no affect your signal in anyway, are you sold yet? You can find these metal covers along with glass replacements on eBay or directly from cnn.cn. Head over to the source link for a quick little how-to.