The Hudson RCI Voldyne 4000 Volumetric Exerciser is designed to accommodate large inspired volumes. The particulate filter screen helps reduce risk of contamination. Its expandable and collapsible tube helps patients find comfortable position for treatments and can be removed when storing the device. Ergonomic swiveled mouthpiece allows to patients create tight seal to enable more accurate measurement. This Spirometer has a flow indicator with smiley face target which makes it easy to use.