I'm so glad that I found this power adapter for my new ResMed 11 CPAP. I recently changed from a ResMed S9 Elite which I had for about 7 years. I had a DC power backup which cost quite a lot of money. I really did not want to have to buy a new power supply and throw away the old one. It would have been a great waste of money. Luckily, I found that this power cord connects to my backup battery and the charger just the same way as my other one. Thanks for saving me a few hundred dollars.