Ancora sul calibro e sulle sue versioni:
Remarks1977-
When introducted in 1977, the 990 with all features was the thinnest automatic movement with date and sweep second; even in 2003 it is only underscored by movements without date and/or sweep second.
micrometer regulator
two serially coupled barrels, one with fixed spring, one with slip spring
Instead of the date ring, an hour angle disc is mounted, which is operated in the crown position for quickset date.
family:
automatic:
989: especially for hour angle
990: date and seconds
992: no date
993: no date, no second
994: no second
manual wind:
995: date and seconds
996: no second
997: no date
998: no date, no second
suffix .1: 25 Jewels
suffix .2: 17 Jewels
Example, year: signature; shock device
1977: 53500047, Longines Swiss, 25 Jewels; Kif-Ultraflex
(Longines 993.1, dial view 995.2)