Bought in 2017 and used until recently. This allows you to keep the factory 2.5" hard drive and add a 3.5" hard drive and quickly switch between the two. The trick to being able to use any drive at all times was the need to update a drive that wasn't used during the last system update. The problem is. Now Sony's Big 1GB update WILL ERASE the hard drive, if you try to update another hard drive that you haven't used in a while you will lose installing additional games/files. You should be able to use the disc afterwards, but the problem will reappear if Sony decides to release a new update. That means you have to keep reinstalling big games. So the only benefit of this add-on right now is the ability to upgrade to a higher-capacity 3.5-inch drive, which in some cases can be a lot cheaper. What used to be pretty cool is now redundant. In short, only buy this if you really want to add a 3.5" PC SATA drive instead of a 2.5" drive.