The 178306-3 is a 12-position, dual-row header from TE's Dynamic D-3100 series, on a 3.81mm mating pitch with a 5.08mm row spacing. Rated 250V, the header fits signal and moderate-power interconnects where a positive locking interface is required.
At 3.81mm pitch and 5.08mm row spacing, the 12-position footprint is denser than the 2.50mm-pitch 4-position peer 1-1871673-2, but shares the same right-angle through-hole termination and detent lock style.
Confirm the mating receptacle part number for your specific wire-to-board or board-to-board application.