What this 3-pin header is built for
The 1719710003: This is a 3-position, single-row, vertical through-hole header from the Molex SL 171971 series, pitched at 0.100" (2.54 mm) — the standard grid for ribbon cable and discrete-wire interconnects. The polarizing key prevents mis-mating with the wrong receptacle — a useful guard in multi-connector panels.
How it mates and terminates
Mates with SL series crimp-housing receptacles (e.g., 70066 series or 70107 series) that accept 22-28 AWG wire. Termination is through-hole solder — the 0.130" (3.30 mm) post length suits standard 1.6 mm PCBs.