You caught me, I was using the chance to show off the Santa beard another time. My wife hated it and threatened me with death in my sleep if I ever grew it back.Like many said it’s the face width a well trimmed upper side of the moustache. After all you don’t wear a mask on your chin…
I use the Crystal-vu since many years and just got the Scubapro solo as a backup mask. If anything leaks it’s usually because of carelessness with the hood which I wear 100% of the time even in warm tropical waters… or a loose strap