It's small changes to the design that increase ease of use and tactile quality. For instance the
link bezel uses a "labyrinth seal" between the bezel and the case so simply turning the bezel while rinsing the watch will eject any sand or
link particles that get between the case and the bezel. And the bezel mechanism is a double-piston design that uses 16 ball bearings which means that bezel action is
link silky smooth.