Introducing The Grand Seiko 60th Anniversary Limited Edition SLGH002, With New Hi-Beat ...

The balance, removed from the movement, has several stories to tell The first of these is the balance spring - it's an overcoil type, which is intended to produce a more perfectly concentric "Breathing" of the balance spring; this is historically a feature of higher-end movements oriented towards precision timekeeping There is no conventional regulator, and without an index for regulating the watch, timing weights on the balance are necessary - this is the first time I can recall seeing them on any Grand Seiko watch, where flat balance springs and conventional regulators have been the rule in the past.

Rolex uses a similar approach in the form of its Microstella balance screws and Patek, of course, has its Gyromax balances Omega uses flat silicon balance springs which are fabricated in such a way as to give the advantages of an alloy overcoil balance spring, and like Rolex, Patek, and now Grand Seiko, also avoids a conventional regulating system by using timing weights on the balance. . Source