It is part of the HD-20 series, the standard-density workhorse for serial and parallel port interfaces, industrial control I/O, and instrumentation cabling where a reliable, field-serviceable connector is needed.
The ground strap and grounding indents in the steel shell provide a low-impedance path from the connector shield to the board ground plane, reducing radiated emissions in unshielded environments. Gold plating on the contacts (mating side) handles repeated mate/unmate cycles without fretting corrosion — rated for the typical 50–200 cycles of a field-service D-sub. The brass base material is standard for signal contacts; the 6 A per-contact rating is enough for low-power signal lines and daisy-chained shield returns, but not for bus-level power distribution. This is the typical arrangement for the cable-end receptacle; the board-mount plug provides the threaded inserts or clearance holes for the mating screw-locks.
The 3-1393480-8 is the same 15-position, right-angle D-sub plug from the same AMPLIMITE HD-20 series, but packaged in a Box rather than a Tray. Both carry the same pinout, shell size, and mounting style; the difference is purely in the shipping quantity and packaging format. For a BOM line that specifies tray delivery, the 5747841-2 is the match.