What it is and where it sits in the series
The Molex 430450412 is the 4-circuit member of the Micro-Fit 3.0 43045 dual-row header series — 2 rows of 2 contacts at 3.00 mm pitch. The 4-position count is the primary BOM variable in this series; everything else (8 A per circuit, 600 V, tin plating at 100 µin, shrouding, locking ramp) is shared with every other member at the same plating grade. What changes across the family is position count and, optionally, contact finish and board-lock feature. Board-to-cable/wire headers in this series are specified into automotive harness midplanes, industrial control modules, and medical device interconnects where a locked, shrouded header survives vibration and accidental unmating. The dual-row layout at 3.00 mm pitch gives reasonable routing density without cramping adjacent traces — the insulation height of 0.390 inches (9.91 mm) is the z-height number the layout engineer holds for board-stack clearance.
What the ratings mean for your choice
The 8 A per circuit rating at the full 600 V is the key pairing for this connector — it is rated for power-duty signal or low-current bus distribution, not just dry-circuit signalling. The tin plating at 100 µin (2.54 µm) is the series-standard finish for this plating grade; it handles the 8 A without issue but wears faster than gold at the mating interface if the application demands repeated reconnect cycles. The contact length of 0.125 inches (3.18 mm) post protrusion is the dimension that governs solder fillet formation in the through-hole — verify your board thickness against this before specifying. The 4-wall shroud, locking ramp, and board-guide feature work as a stack: the shroud protects the contacts from side impact and dust, the locking ramp mates with the receptacle latch for positive retention under vibration, and the board guide pegs the header into the PCB slot to prevent cocking during wave or hand-solder assembly. For panel or through-panel mounting, the board-guide feature is what keeps alignment from drifting during service rework.