The O2 To Go! Cylinder Duration App puts patient and technician's minds at ease. With just the touch of a button, the O2 To Go! App calculates the amount of oxygen remaining (hours/minutes) in a cylinder, giving ambulatory users assurance and peace of mind that they have enough oxygen to be on the go. The O2 To Go! Cylinder Duration App enables users to input settings for a precise readout - including device, liter flow, cylinder size and amount of oxygen remaining in the cylinder.