Board Fit and Mounting Reality
The 10127720-042LF: A board lock on each mounting post anchors the header during solder reflow and takes shear force off the solder joints when the cable is tugged. Gold flash on the male pin mating surface provides a corrosion-resistant interface for repeated mating cycles, though the thin flash means the contact is suited for moderate-cycle-duty applications rather than high-cycle field-service connectors.
The 10127720 base number covers a range of position counts in the same 2-row, right-angle, shrouded format. The 4-position 10127720-042LF is the middle option between the 2-position 10127720-022LF and the 6-position 10127720-062LF.