The 1986718-3 is a 3-position, unshrouded male pin header from TE Connectivity's terminal block header family, designed for vertical through-hole mounting on a 0.138" (3.50mm) pitch. The tin-plated contacts handle moderate mating cycles — fine for field-installed equipment that doesn't see frequent reconnects.
The 3.50mm pitch matches the standard spacing of many terminal block plugs and receptacles — if your BOM calls for a 3.5mm pitch header, this is the pin layout you need. The contact tail length is also 0.138" (3.50mm), which suits standard 1.6mm-thick PCBs with through-hole solder termination.