Home › Portable Oxygen Concentrator Batteries › Internal Battery | AirSep Freestyle 3 | Item BT018-1S Internal Battery | AirSep Freestyle 3 | Item BT018-1S Description Brand new internal battery for the Airsep Freestyle and Freestyle 3 portable oxygen concentrator Default Title - $212.99 $295.00 $212.99 Share 0 Tweet 0 Pin it 0