Grand seiko watch spring drive gmtthe seiko sbge001 spring drive gmt timepiece is a relatively big one it comes with a case diameter of approximately 44 millimetres it has a 9r66 calibre that utilizes elegantly seikos spring drive technology and features 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 this watch is equipped with a dual ti