Get the most out of your AirSep portable oxygen concentrator with the AirSep AirBelt Battery. This external battery will work with all 3 AirSep portable oxygen concentrators: the AirSep Focus (with adapter), AirSep FreeStyle 3, and AirSep FreeStyle 5. Weighing in at 1.8 pounds, the AirBelt Battery is designed to be worn around your waist, adding no weight to the concentrator itself. To recharge the AirBelt Battery, use the custom AC power supply that comes with it. For the FreeStyle 3, expected battery life with the AirBelt ranges from up to 10 hours on setting 1 to up to 5 hours on setting 3. For the FreeStyle 5, expected battery life with the AirBelt ranges from up to 7 hours on setting 1 to up to 2 hours on setting 5. The AirSep Focus provides up to 4 hours of battery life on setting 2 when using the AirBelt Battery. This external battery allows you to significantly extend your portable oxygen therapy time while keeping your concentrator lightweight and easy to carry.