The JST 03HR-4K-P-N is a 3-position IDC receptacle from the HR series, designed for discrete 24 AWG wire. This is the connector you'd pick for a 3-circuit power or signal tap where you want to press the wire into place rather than crimp each terminal individually.
IDC termination, 24 AWG — no crimp tool needed
The 03HR-4K-P-N uses IDC (insulation displacement) termination: you lay the 24 AWG wire across the slot and press it home with a simple hand tool or arbor press. The contact's tines slice through the insulation and bite into the conductor — no wire stripping, no crimp die selection. That makes this connector fast to assemble in low-to-medium volume harness work, but the trade-off is that the wire gauge is fixed at 24 AWG; you can't swap to a different size without changing the housing. The detent lock on the side snaps into the mating header's groove, holding the pair together against light vibration — it's not a latch you'd trust under heavy cable strain, but for an internal wire-to-board connection it's adequate.