The 90 series is an updated automatic watch movement produced by Miyota. Compared to the previous Miyota 82 series, the Cal. 9xxx models feature 28,800 A/h operation, hacking seconds, and are substantially thinner. Importantly, the wheel train is redesigned so the seconds hand is in the direct power flow, eliminating the “flutter” that was a signature of the previous family.
Distinguishing features of the movement include three screws holding the central winding rotor in place. When viewed from the back with the winding stem at 9:00, the balance wheel is located at 7:00 and is located by a counter-clockwise cock.
The 90 series was introduced at BaselWorld in 2010 with the 9015, 90S5, and 9100. The first Cal. 9015 movements were shipped in July or August 2019. The slim no-date Cal. 9015 was added in 2018.