It is a board-to-board interconnect component designed for through-hole solder termination to a PCB. The 0.100" (2.54mm) pitch is the standard spacing for BergStik headers, compatible with a wide range of mating receptacles and IDC connectors.
The 100.0 µin (2.54 µm) tin thickness on the mating side is a robust plating that resists fretting in low-insertion-force applications. The 0.100" (2.54mm) pitch and 26 positions in a single row give a total body length of about 2.6 inches. The overall contact length of 1.058" (26.87mm) includes a 0.830" (21.08mm) mating pin and a 0.128" (3.25mm) solder tail. The 0.100" (2.54mm) insulation height means the header sits close to the board surface, which is the point of an unshrouded design — you trade pin protection for a lower stack height.