Board Fit and Wire-to-Board Role
The 3-641208-4: The single-wall shrouding protects the mating pins from one side, leaving the other three sides open. This is a space-saving design for applications where the mating housing is inserted from a known direction, typical in general-purpose and industrial equipment.
The base product number is 641208, which is useful for searching the full MTA-156 family.
Comparison with Peer Alternatives
That part uses tin mating finish (vs gold on the 3-641208-4) and includes a board lock for SMT retention. The pitch difference alone means they are not footprint-compatible — the 3-641208-4's 3.96 mm pitch is wider and suits larger wire gauges.