Pitch, positions, and the board footprint
The 3-641208-9: The 0.156" (3.96mm) pitch sets the board footprint and the per-contact current ceiling — at this spacing, the header mates with standard MTA-156 receptacles and accepts 18-22 AWG wire, with the current rating varying by wire gauge. 9 positions, single row, all loaded — the board layout needs one row of through-hole pads at 3.96mm centers, with the 0.125" (3.18mm) post length fitting standard 1.6mm PCBs.
Gold mating face and friction lock for field service
The friction lock holds the header to the receptacle without a secondary latch — it resists vibration-induced disconnect in industrial panels and general-purpose equipment.
Comparing to the 8-position sibling
The 9-position 3-641208-9 shares the same 0.156" pitch, single-row layout, friction lock, and gold plating as the 8-position 3-641208-8.