The EasyOne™ Spirometer incorporates an ultrasonic flow sensor to measure the flow of air in and out of the patients lungs. Ultrasonic flow measurement eliminates problems associated with traditional methods of flow measurement There are no moving parts, no codes to enter, no screens to catch sputum, and no disposables to calibrate. Ultrasonic flow measurement is independent of gas composition pressure, temperature, and humidity; and eliminates errors due to these variables. The Ndd EasyOne Spirette is disposable and acts only as a hygienic shield and is transparent to the ultrasonic pulses traveling between the measurement transducers. Since the disposable spirette has no sensor elements, it does not perform a measurement function and does not require calibration.