If there is an intake and exhaust "pipe" on these masks, how can you dive under water? Unless there's some type of pressure regulating release on the exhaust, won't the mask squeeze in? Your nose stops that after pressurizing on a regular mask. Am I missing something?
But I agree with the concept that if someone uses this because they're uncomfortable using a regular snorkel, they probably should get some water time and master a regular snorkel and mask.
It's not for diving underwater. It's not for people who want to take up free diving or scuba diving. It's for people who want to spend a half hour on their Caribbean vacation floating around a shallow reef and looking at some fish, without stepping up their game to scubaboard levels.
If the consensus is that this simply can't be done safely, then I guess it's not a good idea. But so far I haven't seen any evidence presented to that effect, which is what I was looking for.