What this 3.96 mm pitch header does that a 2.54 mm one cannot
The 2-647123-8 is an 8-position, single-row, shrouded 4-wall header from TE's MTA-156 series, with a 3.96 mm pitch that leaves room for heavier wire gauges than the common 2.54 mm pitch headers.
Board footprint and wire gauge fit
The 3.96 mm pitch means the through-hole footprint is wider than a 0.100" header — verify the board layout accommodates the 0.156" hole spacing. The 0.125" post length (3.18 mm) is standard for a 1.6 mm PCB; the 0.300" mating pin length (7.62 mm) reaches into the mating receptacle.
The header is through-hole solder termination — no press-fit, no IDC.