If you are diving in cold water, that big metal flange on the Halcyon bag rocks . . . you can stick it in the corner of your mouth and form a seal around it. I will be interested to know if you can do that with the plastic one on the DIRZone bag. I agree that the price of the Halcyon bag is painful -- even in the US it is -- but I just finally gave up and bought them, because I tried a bunch of other ones and nothing worked as well for me when my face is cold.