The 3-641209-7: This is a single-row, shrouded header from the MTA-156 series, designed for wire-to-board power distribution. The 0.156" (3.96mm) pitch gives it a wider footprint than fine-pitch signal headers — it suits applications where the board trace needs to carry a few amps without tight routing constraints. The 7 positions are all loaded, and the header mates with the matching MTA-156 receptacle housing (crimp or IDC).
Contact plating and current handling
The post side is tin, which solders cleanly into a through-hole board. For a given wire size, the MTA-156 contact can carry several amps; the derating curve in the product drawing gives the safe limit at 105°C.