The present invention is an improved air cylinder for air mattresses primarily intended for hospitals, long-term care facilities and in-home use. Each elongated flexible air cylinder contains a foam member with a generally square cross-section and area to enclose a volume of air above the foam member. When one or more air cylinders are connected to a pump and pressure to air cylinders is increased, the area above the foam members enclosed by the flexible air cylinders inflates with air. The volume above the foam member in each flexible air cylinder can retain enough pressure to lift the portion of the patient's body above that air cylinder away from the resilient foam member. The flexible air cylinders may be connected to achieve an alternating pressure cycle where one set of air cylinders may be pressurized while other air cylinders are allowed to evacuate air and become depressurized.
