FD 983 is a small-format, long-stroke door latch designed for use in large and heavy doors. It is designed to provide access control by integrating a driving motor to lock or unlock the latch, and is equipped with a manual override switch in the event of a power failure. The latch features three adjustable backset lengths, allowing it to fit a variety of door widths. It also has an adjustable closing force and an adjustable torque to resist mechanical stress and wear. This latch also includes a variety of accessories such as an extension plate, an internal cover plate, an external cover plate, a deadbolt and an optical sensor, allowing it to be adapted to different applications.