The Tranquility Auto system provides various levels of pressure. The pressure delivered at any time is based on your needs. The APAP system makes repeated measurements and tests of air flow and pressure to provide automatic adjustment of the therapy. The pressure is controlled by a microprocessor that monitors flow and a pressure transducer to provide accuracy and comfort and adjust to changes in elevation. The Tranquility Auto (Model 7410) system from Respironics, is a medical device that includes a microprocessor. The microprocessor receives information from a flow sensor and pressure transducer and processes this information in order to adjust the blower to deliver the pressure that you require. Additionally, this compact unit features an initial ramp, a convenient handle and an easily replaceable or washable filter.