The 0.100" pitch is the bread-and-butter spacing for 0.025" square posts — it fits standard perfboard and mates with the matching BERGSTIK receptacle or any industry-standard 0.100" IDC socket. It is not the choice for frequent field disconnect, but for a board-to-board stack that gets mated once in production, it is a cost-effective fit.
This is a through-hole part. The 0.095" (2.41 mm) solder tail length suits standard 0.062" PCBs. The overall contact length of 1.238" (31.45 mm) gives a generous 1.043" (26.49 mm) mating length above the insulator, which means the header stands tall enough to reach into a shrouded receptacle housing.