Invacare - Cylinder Backpack holds most oxygen M2 thru M9 cylinders and can be used as a backpack, fanny pack, or shoulder bag. Includes internal hook and loop strap to hold cylinder in place, ventilated shoulder straps, zipper pull, top handle for carrying or hanging, grommets for cannual placements, lanyard and hook for keys and pockets for storage. Invacare Cylinder Backpack offers added mobility and comfort while using M2 through M9 oxygen tanks. Color: Black and grey. Size: 16" H x 10" W.