The MC41P-388 Series World Time Zone Master Clocks is used as a master control for ATS World Time Zone Clocksto provide a complete stand-alone system for up to 15 World Time Zones.GMT (Greenwich Mean Time) is used as the reference time. GMT time, GMT date, GMT day of the week, time zoneoffsets (including 1/2 hour offsets), and any seasonal adjustments are easily programmed for up to 15 different worldtime zones, using the built-in keyboard and alpha-numeric display. Auto-Prompt, cursor guided programming makesset up quick and easy.