Grand seiko watch spring drive gmtgrand seiko sbge005 is a gmt spring drive timepiece that makes use of seikos unique technology the timepiece is equipped with 9r66 automatic calibre that has 30 bearing jewels the movement comes with a 72 hour power reserve it is protected from water penetration and magnetic influences a power reserve indicator is available for the convenience of the wearer grand seiko sbge005 features a 24 hour gmt display a date window is positioned at the 3 o clock mark