Grand seiko watch spring drive chrono this timepiece belongs to the spring drive chronograph calibre 9r86 series by grand seiko it comes with 9r86 calibre that features 30 bearing jewels the calibre is protected from water penetration and magnetic fields seikos specially crafted spring drive movement makes this timepiece exceptionally special the escapement mechanism is replaced by a seiko regulator a mechanical stem stores energy the watch comes with a 72 hour power reserve and a power r