The 644874-4: With 4 positions loaded, the header occupies a compact 0.400" (10.16mm) of board edge, leaving room for adjacent connectors on tight layouts. The kinked pin solder termination provides mechanical retention in the plated through-hole before wave soldering — the kink acts as a press-fit interference that holds the header upright during assembly.
Mating half and locking: friction lock compatibility
The single-wall shroud (shrouded-1 wall) protects the mating pins from accidental shorting against the board or chassis, but does not provide the full polarization of a 4-wall shroud — orientation is guided by the friction lock keying, not by a shroud wall.
For a typical 22 AWG wire in a 25°C ambient, the MTA-100 system is commonly rated around 5 A per contact, but derate above 25°C per the product derating curve. Voltage rating is 250VAC, which covers most signal-level AC and DC circuits in industrial control, instrumentation, and consumer electronics.