The 1-178137-3 is a 6-position, 2-row header from TE's Dynamic D-3100 series, on a 3.81mm pitch.
All 6 positions are loaded, so no blank spots in the connector body.
Contact finish and retention
The detent lock gives a tactile snap when mated — it's not a latch you can release without tools, but it holds against moderate vibration better than a friction-only fit.
