3 ms·
There is a system of valves that keep the air flowing in just a single direction. Also, there are additional seals inside the mask that keep the exhalation dead
by dougmwne 5y ago
There is a system of valves that keep the air flowing in just a single direction. Also, there are additional seals inside the mask that keep the exhalation dead space to a small area just around the mouth and nose, not the entire inner area of the mask and snorkel.