The 3-643813-4: The closed-end design means it terminates the end of a wire run; there's no pass-through for daisy-chaining, which simplifies harness routing when you want a clean stop at the last device.
Locking Ramp and IDC Termination — What That Means in the Field
No secondary lock, no screw, just an audible snap when it's home. The IDC termination punches through the 22 AWG insulation and grips the conductor in one stroke; the tin plating at 80.0 µin (2.03 µm) is thick enough to survive the IDC slot's cold-flow without cracking, but it's tin, not gold, so mating cycle life is in the tens, not hundreds. For a harness that gets assembled once and stays put — inside a control cabinet, on a conveyor, behind a panel — that's fine. If you're mating and unmating every shift, you'd want a gold-plated sibling in the MTA-100 line.