The volume of air trapped in the bag is measured in litres and for all practical purposes represents a person"s lung volume, though a small portion of air always remains in the lungs.  
Lung Volume Kit is used to measure vital capacity, the volume of air a person can expel after taking the deepest possible breath.
Comparisons can be made between a persons lung volumes and such factors as height, age, physical activity and smoking habits.

Biology School Lab Equipment Suppliers in India 

Ltekonline are the manufacturers of Lung Volume Kit Health Testing Kits used to demonstrate engineering principles in Engineering Colleges, Engineering Schools and Biology Laboratory Equipment for Engineering Teaching Lab in Universities