I not a 'watchologist' either . all my watches are all Rotor Auto, or manual wind. only battery electronic watch I got is the cell phone. ( me )..if it not all gears, springs, pivots,and levers, I don't really want to wear it .
A couple people already mentioned it's a 'GMT ' hand movement . . also there is couple mechanical builds of GMT calibers . ( office ) and ( true / traveler ) .
( Basically ) ..The GMT hand runs separate from the watches Hour and minute hands that make 2 revolutions of 12 hr. time for timekeeping . the GMT hand runs independently set to another time zone, making only one 24 hr. revolution . and like Mil. Time is kept with 24 Hr. markers on the Bezel . GMT set, is basically just a pull-out marker, when you pull out the Crown-stem, that separately mechanically operates setting of the GMT hand when rolling the Crown clockwise.
Now a few other High-end brand names that use a GMT True or traveler mechanical Caliber . Models like, Rolex GMT, Grand Seiko GMT, Omega sea master GMT, Tudor black bay GMT ...etc
Difference with a mechanically true/traveler GMT, dual time function. The hour-hand movement can be set independently in one-hour increments without hacking the movement. So basically it moves/sets the hour hand in one-hour increments to a local time without stopping or moving the minute and seconds hands, or affecting the GMT hand .
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