The SP-580Q 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. 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 Hyperdry SystemThe 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. High Flow PurgeThe High Flow Purge design used on TUSA snorkels offers a covered large diameter purge valve for simple, quick clearing, reducing the amount of water remaining in the mouthpiece in an instant.