The new 9RA5 Spring Drive calibre. Info taken from here: https://watchesbysjx.com/2020/03/gra...m-slga001.html

Improvements over the current 9R65:

* power reserve lengthened to 120 hours, with two mainspring barrels in series

* date change now instant

* accuracy improved from 15 seconds a month to 10 seconds a month, with thermo-compensation (previously only seen in the quartz movements) and oscillator and temperature sensor vacuum-sealed

* slimmer: 5.0mm against the 9R65's 5.8mm, with the magic lever and gear train redesigned to take up less space

The first watch it'll be fitted in will be a limited edition Grand Seiko diver.

For those, unlike me, able to appreciate such things, there are photos of the various parts of the mechanism in that SJX piece. (For those who like complaining about the size of GS divers, there are also renders of the new titanium SLGA001)