The natural PA66 body carries the 4.20mm pitch and row spacing that defines the Mini-Fit Jr footprint — the same spacing on both axes means the terminal pockets are evenly distributed and the crimp tooling is consistent across all positions.
The Contacts-Not-Included Reality
You order the 0039012145 shell separately from the 5557-series female crimp terminals (Molex 44476-0012 or equivalent). The terminal is a stamped-and-formed socket that crimps onto 18-24 AWG wire and locks into the PA66 pocket with an audible click. If you are re-pinning an existing harness on site, you need the terminal and the correct crimp tool (Molex hand tool 63811-8700 or a press with the 207129-series die set). The housing alone is just the plastic frame — no continuity until you load the contacts.
Mating and Latching
The latch lock is a molded ramp on the receptacle that snaps over the corresponding tab on the Mini-Fit Jr header. It gives a positive tactile and audible click when fully seated — you feel it lock. No secondary lock or TPA is required for basic retention, though the 5557 series does offer a panel-mount option if the harness runs through a bulkhead. The free-hanging mount means this housing floats in the harness; the latch takes the strain, not the crimp barrels. For a field repair, check that the latch ramp is not cracked — a broken latch means the pair can separate under cable pull.
That covers most indoor industrial cabinets and automotive under-hood (non-engine-block) locations. PA66 absorbs moisture over time — the mechanical properties are stable within that range, but the natural colour will yellow slightly under UV if the harness sits in direct sunlight. For outdoor or washdown environments, the Mini-Fit Jr family also offers a CPA (Connector Position Assurance) version with a secondary lock; this standard latch-lock housing is fine for dry interior locations.