126710BLRO The Rolex GMT-Master II was designed for the man whose work and play spans different time zones. If you are that man. you will experience the pleasure of a sturdy 40mm stainless-steel case that has a screw-down case back and winding crown. Enclosed in the case is the Rolex Calibre 3285, a self-winding mechanical movement with dual time-zone, stop second and date functionality. This caliber has a -2/+2 sec/day precision and has a power reserve of up to 70 hours. The dial is black with hour markers made from 18 carat gold to prevent tarnishing.