Whether you are doing household chores or simply lounging around in your favorite chair, the AC power supply lets you charge your Activox Pro anywhere in the vicinity of a standard US or Canadian wall outlet. This means you can get back to what you were doing and enjoy all the benefits of supplemental oxygen while the battery is being recharged. The internal battery takes approximately 4.5 hours, while the external battery takes approximately 3 hours to fully recharge with the AC power adapter. The AC power supply is a must in order to be able to charge throughout your home, and if you plan on traveling this will be an accessory you will want to be sure not to forget in your accessory bag. This power supply operates on 100 – 240 VAC, 50 – 60 Hz, making it versatile for various power sources.