Apple is screwing with screws, again.If you want to remove the outer casing on your iPhone 4 to replace the battery or a broken screen, it won't be easy anymore. In the past, you could use a Phillip screwdriver to remove two tiny screws at the base of the phone and then simply slide off the back cover.But Apple is replacing the outer screw with a mysterious tamper-resistant screw across its most popular product lines, reports iFixit, a Web site that provides free repair manuals and advice forums mostly aimed at Apple products. Apple calls them "Pentalobular" screws. Here is what they look like:New MacBook Pros, iPhone 4s and MacBook Airs will have the Pentalobular screw, making it harder for do-it-yourselfers to make repairs. What about existing products in the field? Pentalobular screws might find their way into them, too."Apple's latest policy will make your blood boil," says Kyle Wiens, CEO of iFixit. "If you take your iPhone 4 into Apple for any kind of service, they will sabotage it by replacing your Phillips screws with the new, tamper-resistant screws. We've spoken with the Apple Store geniuses tasked with carrying out this policy, and they are ashamed of the practice."Apple Stores now carry a large supply of the Pentalobular screws, and Apple technicians have been ordered to replace the Phillip screws with Pentalobular screws in every device they service, according to Wiens. Apparently, you won't get your Phillip screws back.But iFixit has found a workaround: a driver that works on the flowery 5-point Pentalobular screw, at least to hack out the screws so that you can replace them with standard Phillip screws (assuming, of course, that you have the right size Phillip screws). Wiens doesn't run across this kind of screwy behavior from many consumer electronics manufacturers, Apple and Nintendo being the only exceptions. So what is Apple thinking?For starters, do-it-yourselfers fiddling inside Apple products, maybe even swapping in unauthorized components, can wreak havoc on the Apple brand by creating a plethora of customized devices. Apple's success is built on controlling the user experience.This isn't the first time Apple has used screws to gain an advantage. Apple had been using 5-point Torx screws for its MacBook Pros, not standard 6-point Torx screws."We did a little bit of research and found out that this particular screw has been patented," Wiens says. "It is illegal to import screwdrivers that can open this screw into the U.S. unless you buy it through Apple's sales channels. Apple sells the screwdriver for $40." (Wiens doesn't know if the Pentalobular screws have been patented.) With the MacBook Pro Core i5 released last year, though, Apple seemed to be getting out of the screwdriver business. Apple switched from the patented 5-point Torx screw to the more common Tri-Wing screw. All of which makes the recent about-face to the tamper-resistant Pentalobular screw somewhat of a mystery.But there might be one more clue: follow the money. Wiens figures that the more common Tri-Wing screw drew complaints from Apples' authorized independent laptop service centers that were losing business because do-it-yourselfers could use standard screwdrivers. Apple, of course, gets a cut of service jobs\u2014and the Pentalobular screw brings back the monopoly. Only Apple authorized service technicians have Pentalobular screwdrivers, says Wiens, and they're not allowed to resell them."Apple sees a huge profit potential," Wiens says. "A hundred dollars per year in incremental revenue on their installed base is a tremendous opportunity." Tom Kaneshige covers Apple and Networking for CIO.com. Follow Tom on Twitter @kaneshige. Follow everything from CIO.com on Twitter @CIOonline. Email Tom at email@example.com.