Compressors for medical purposes; Nebulizers for respiration therapy; Compressor nebulizer system, namely, a compressed air operated nebulizer and a compressor sold as a unit for respiration therapy; Peak expiratory air flow meters; Oxygen conservers for medical applications; Oxygen compressor systems for transfilling portable metal gas cylinders with pressurized oxygen for ambulatory patient use; Portable medical oxygen storage and delivery system for ambulatory use, namely, a compressed oxygen cylinder, an oxygen pressure regulator and flow controller, and a carrying case sold as a unit; Oxygen apparatus for medical applications and parts therefor, namely, oxygen concentrators, and replacement sieve beds for oxygen concentrators; Oxygen cylinders, oxygen cylinder carts, oxygen cylinder carrying cases, oxygen cylinder regulator valves, oxygen valve wrenches, oxygen tubing, oxygen tubing connectors, nasal cannulas and oxygen humidifiers, all for medical applications; Bags, pouches and racks adapted for carrying oxygen cylinders; Medical devices, namely, pulse oximeters; Humidifiers for use in connection with medical respiratory devices, humidifiers for providing moisture to patients' airways; Respiratory masks for medical purposes and parts therefore, namely, mask cushions and forehead pads; Apparatus for diagnosing respiratory conditions; Apparatus for treating respiratory conditions; Medical oxygen concentration sensors for monitoring the concentration of oxygen used by patients