The new Portable Ventilator 73X is the first affordable model designed for mass casualty care. 6 hours of continuous run time with internal compressor or 11 hours with 02. No pressure cycling, no auto cycling, no position sensitivity, no wasting of precious oxygen. It has an internal rechargeable battery pack, comprehensive alarm system, digital airway pressure gauge & battery charge indicator. The 73X uses inexpensive ventilator circuits and can be used with/without HEPA or Chemical Bio filters.