Grand Seiko Cal. 9S85 is a high-beat automatic movement with date. It is closely related to Cal. 9S86, which adds an independently-adjustable central GMT hand. It was introduced in 2009 and remains in production as of 2020.
Cal. 9S85 features a proprietary Spron 610 alloy for the mainspring, with improved impact and magnetic resistance. The escapement is created using MEMS technology for precision. The mainspring is constructed of the Spron 530 alloy for higher torque and increased power reserve. The movement is reportedly resistant to magnetic fields to 4,800 A/m.
Cal. 9S85 is used in the Grand Seiko Hi-Beat Automatic SBGH series of watches. The similar 8L55 is used in the Prospex SLA Hi-Beat dive watch line. In 2018, Grand Seiko introduced a V.F.A. version of Cal. 9S85 tuned to deliver -1/+3 seconds accuracy.