While I'm not going to call Squale disingenuous about their water resistance rating but I'm curious how they managed 500m on the 1521. There are other big players in the market that have less (or comparable) water resistance but are adding additional features to prevent crystals blowing off, etc. while the Squale appears on the outside to be a pretty typical dive watch.
Seiko MM300 - 300m - Monoblock Case
Omega Seamaster - 300m - Helium Escape Valve
Tudor Pelagos - 500m - Helium Escape Valve
So what am I missing here? What did Squale do to achieve 50 Atmos without a helium escape valve or monoblock case?