This hand held spirometer measures lung capacity without the need for water. Its advantages over the conventional tank-type spirometer are its portability and ease of operation enabling it to be used for physiological experiments out in the field as well as indoors.Lung capacity is simply measured by breathing out through the mouthpiece and recording the readout on the dial.Range: 1000-7000 cm³Supplied with 50 plastic mouthpieces & full instructions