The beauty of the AirSep FreeStyle 3 Universal Power Supply is that it combines the AC and DC power supplies into one convenient solution. Whether you are relaxing at home, traveling the country, or heading to a friends house for dinner, this universal power supply will ensure you don't go without oxygen. Simply plug the AC power cord into a 110v wall plug or plug the DC power cord into a 12v car charger and you will be good to go. With some portable oxygen concentrators, the DC power supply doesn't recharge the battery on certain oxygen settings. With the AirSep FreeStyle 3 Universal Power Supply, you can use the unit on all 3 pulse flow settings and it will not only recharge your unit but it will power the machine to keep your oxygen levels saturated. This all-in-one power solution provides ultimate flexibility for both home and on-the-go use.