This is the Tusa Imprex II Hyperdry Snorkel with Purge and Crystal Silicone Flex Neck Features: Hyperdry System Large capacity drain chamber and oval purge valve with internal purge channel Ortho-consciously designed mouthpiece for ultimate comfort Crystal silicone flexible neck The Imprex II Hyperdry snorkel has a special internal purge channel located below the mouthpiece. It channels exhaled air out the top of the snorkel while excess water drains through the bottom purge valve. The Hyperdry System keeps the main pipe dry by ejecting water through an independent escape pipe. This unique design utilizes the angle of the snorkel pipe and the resilience of the water surface to eject water.