Take a look at the iPhone 4S video on Apple.com webpage and you will notice that the iPhone 4S in the video has pentalobe screws holding the back case together. No big deal since DirectFix.com has the pentalobe screwdriver to assist you in the take apart of the unit when you need to repair it. We also have replacement pentalobe screws if you happen to loose one. The pentalobe screw driver is part number IP-2466 for $6.99 and free shipping. The pentalobe replacement screws part number IP-2468 and run $4.99 with free shipping.
Screen Shot of the iPhone 4 video from Apple Showing the Pentalobe Screws
Apple iPhone 4/4S Pentalobe Screwdriver 5-Point - $6.99
Apple iPhone 4/4S Bottom Screws 5-Point Pentalobe - $4.99