We purchased a Portable Outlet backup battery for my husband's CPAP machine. We read the description and watched the Portable Outlet video. The battery came, and upon trying to use it, we discovered it was NOT a backup battery but an alternate power source. I also discovered through YouTube videos that this is an older unit, not the newest unit which does act as a backup. They don't even carry the newest unit. When I called the company to return it, I was told their policy states that once opened, they do not accept returns because they are medical devices. This is NOT a medical device--it is a battery that can be used for not only medical devices but cell phones, even outdoor televisions! They will not work with you. Very angry about this... Just lost $300+!