Use ultrasonic time difference to get spirometric parameters, Gasboard-7020 Handheld Pulmonary Function Tester is widely used for the VC, FVC, MVV testing in the respiratory internal medicine, pulmonary medicine, tracheitis medicine, surgery etc. 1?Test instruments used in respiratory internal medicine, pulmonary medicine, tracheitis medicine, surgery etc. 2?Preoperative Pulmonary function tests. 3?With the needs of the internal medicine diagnosis and treatment. 4?To meet the needs of the cardiology medical work. 5?The physical examination of the company and the school. 6?To meet the needs of industrial hygiene.