airflow attenuators and resistors specially adapted for use in connection with continuous positive airway pressure therapy machines and medical ventilators; medical apparatus, namely, continuous positive airway pressure devices, variable positive airway pressure devices, and bi-level positive airway pressure devices; medical apparatus, namely, positive airway pressure devices designed to treat sleep disordered breathing; pressure adjusting feature sold as a component of continuous, variable, and bi-level positive airway pressure devices; medical apparatus embedded with software that adjusts air pressure of positive airway pressure devices in response to breathing cycles monitored by sensors; oxygen concentrators; respiratory masks for medical purposes; cpap masks; masks; medical devices