The 1658525-4: It is a vertical through-hole mount connector with two rows, all positions loaded, and a blue housing. Typical use is in internal board-to-cable interconnects where a parallel ribbon cable transitions to a DIP footprint — common in legacy I/O, prototyping, and control card wiring.
The cable pitch of 0.050" (1.27 mm) is the primary compatibility check — your ribbon cable must match this spacing for the IDC contacts to align. The connector accepts 26-28 AWG stranded or solid wire; using wire outside this range risks an unreliable IDC gas-tight joint. The feed-through feature lets the ribbon cable pass through the header to daisy-chain to another connector, which simplifies multi-drop harness layouts without a separate splice.
For high-cycle or corrosive-duty applications, a gold-plated variant would be specified. The IDC termination mass-terminates all six conductors in one press operation, eliminating individual crimping and reducing assembly time on the harness build.
The closest functional sibling in the same Series 622 is the 1-216791-6, a 16-position DIP header with the same 0.050" cable pitch and 0.100" board pitch. The key difference is position count — 6 vs 16 — which changes the PCB footprint length. Both are active, RoHS compliant, and use IDC termination. Choose the 6-position for low-channel-count signal runs; step up to the 16-position when your BOM calls for more I/O on the same pitch.