The L990 was Longines' last 'in-house' automatic movement.
Several variations of this movement exist, like the L989 for use in Hour Angle watches, the L992 without date, the L993 without date and seconds et cetera.
The .1 versions are fitted with 25 jewels, while the .2 versions have 17 jewels.
After its discontinuation by Longines the design lived on in the Lemania 8810. In updated form (Lemania 8815) it also served in watches from high-grade manufacturers like Breguet.