The unshrouded design means it relies on the mating receptacle housing for polarization and keying — common in ribbon cable IDC assemblies and general-purpose wire-to-board harnesses where the header lives on the PCB and the cable plugs on.
The 0.100" (2.54mm) pitch is the de facto standard for 0.025" square post headers — the footprint is universal, so board layout is straightforward.
The overall contact length is 0.538" (13.67mm), with a mating length of 0.318" (8.08mm) and a solder tail of 0.120" (3.05mm) — enough for standard 1.6mm PCBs.