Bring a tank along… you may need it… The oxygen tank sleeve attaches to the back of all MobileAid Easy-Roll stations or bags. Secures oxygen tanks (up to 4.3″ diameter and up to E or M-24) firmly to the back of the bag frame. Easily secures to frame in just seconds with Velcro wrap-around supports. Includes pouches for adult and child oxygen masks. [Oxygen Tank NOT Included]