What This Jackscrew Does in the Assembly
The 5205818-3 is a jackscrew socket from the TE AMPLIMITE HD series — a threaded hardware accessory that secures the mating halves of a D-sub connector. It carries a 4-40 socket on one end and a 4-40 screw on the other, with a length below head of 0.312" (7.92 mm). This is the female side of the jackscrew pair; it threads onto the male screw lock of the mating connector half to draw the shells together and keep them mated under vibration.
Compatibility — Which Connectors It Fits
This jackscrew is listed for use with AMPLIMITE Series HDF and HDP connectors. Those are high-density D-sub families — the 5205818-3 provides the mechanical lock for the shell, not the signal path. If you are building a cable assembly with an HDF or HDP plug and receptacle, this is the hardware that keeps the pair from backing off under cable strain or cabinet vibration.