What the 3.96mm Pitch and 2 Loaded Positions Mean for Your Build
The 3-644742-1: This MTA-156 header carries a 3.96mm pitch — wide enough to route a single 18–22 AWG wire per position without crowding the board trace or the mating receptacle. The 3-position housing ships with only 2 positions loaded, which is a common pattern when one pin serves as a ground or keying placeholder; verify your harness schematic expects two active circuits, not three. The gold mating finish at 30 µinch handles moderate-cycle industrial use — think 50 to 100 matings in a bench tester or control panel where the connector is disconnected quarterly. Tin on the solder post keeps the board-level joint cost-effective. Friction lock holds the header to the mating receptacle with a simple ramp-and-detent — it keeps the pair together under light vibration or cable tug, but won't survive the shock profile of a vehicle or a machine tool spindle. For those environments, look at the MTA-156 with a positive latch.
The natural colour insulator is a visual cue that this is the unkeyed version; some MTA-156 housings use colour to indicate polarization.