The 0.156" (3.96mm) pitch gives enough spacing for 20-22 AWG power wiring without forcing a wide connector footprint.
This is the most common sourcing miss on this part: the BOM line for the housing alone leaves the harness builder short when the assembly station runs. Add the crimp terminals to the same RFQ to avoid a split shipment.
Mating half and orientation
This receptacle mates with the JST B3P-VH series pin header (through-hole, right-angle, or vertical variants). The housing is polarized — the latch lock and internal keying prevent reverse insertion, so the harness builder cannot mis-mate the pair on the line. Free-hanging (in-line) mounting means the receptacle sits on the wire bundle, not on the board; the header takes the PCB footprint.