Through-hole solder termination — the 0.125" (3.18mm) post length gives a solid solder joint on a standard 0.062" board. The 0.125" (3.18mm) insulation height leaves clearance under the header for trace routing.
The closest functional second-source is the 1-292164-1 from the CT series — also a single-row, unshrouded header with tin contacts, but with 11 positions on a 0.079" (2.00mm) pitch and a right-angle orientation. The 640383-8 gives you a wider pitch (3.96mm vs 2.00mm) for easier routing and a vertical through-hole mount, while the 1-292164-1 offers a higher circuit count in a denser footprint.