What is a Medical Three Ball Incentive Spirometer used for ?

Three Ball Incentive Spirometer is widely used in hospital and home care . 

One person use this Three Ball Spirometer, With the help of slow breathing to strengthen respiratory muscles, the patient slowly sucks up the sphere, so that the rib muscles expand outward to the chest wall to better expand the pile, prevent the ventilation of alveolar collapse, improve the vital capacity to strengthen the lung swelling and cough ability, and prevent sputum accumulation.

By inhaling air through the trainer, the external intercostal muscles and diaphragm muscles are contracted to make the anterior and posterior diameter of the thoracic cavity and the upper and lower diameter