The housing accepts discrete wires or ribbon cable, and the feed-through feature allows daisy-chaining multiple receptacles on the same wire run.
The housing mounts free-hanging (in-line) or right-angle.
Comparing 4-640620-2 and 4-640620-1
The 4-640620-2 and 4-640620-1 are both 12-position MTA-100 IDC receptacles with the same pitch, termination, and locking ramp. The difference is the housing color: the -2 is red, while the -1 is a different color (typically blue or yellow depending on the variant). No functional spec — current rating, wire gauge, or plating — changes between them. Choose by color-coding preference for your harness.