The function is in principle very well. He holds tightly to wet conditions and can be used comfortably.
BUT: As in another review already erwäht he tends to do after exhaling at the Oberlfäche close and so deep breathe to block after Auftachen. At the beginning of the shock is yet reltaiv large.
With a little practice - especially the position of the head - is this phenomenon to circumvent.
All in all a solid snorkel, a point deduction for the "shock factor"