The Seiko Gen 1 (1st Generation) 7A28-7120 Royal Air Force flight crew issued military analog chronograph watch was the first quartz chronograph watch issued to Her Majesty’s armed forces, with October 1984 being the first date of issue.
This piece produced in August 1984 is thus one of the first issued of a total run of 11,307 Gen 1 chronographs, which were not replaced until November 1990.
The caseback is inscribed with the "broad arrow" and NATO Stock Number (NSN) 6645-99 7683056 used for military-issued equipment:
6645 = Time Measuring Instruments
99 = NATO Country code United Kingdom
768-3056 = individual part number
In contrast to the commercial versions, the issued version has a 37mm diameter case with matte, bead-blasted finish, fixed strap bars and a "circle P” dial, indicating radioactive Promethium lume.
The 3:00 o’clock register measures 1/10ths of a second, while the large center hand measure elapsed seconds. The 9:00 o’clock register records chronograph minutes up to 30 while the bottom register is a continuous seconds hand.
The 7A28 (Gen 1) reference is Seiko's first analog chronograph, impressively over-engineered with metal gears and a 15-jewel movement which is able to be serviced and maintained. It takes a SR936SW (394) 9.5 x 3.6mm battery.
