Board Fit and Routing with 0.100" Pitch
The 66925-017: This is the standard pitch for prototyping and general-purpose board-to-wire interconnects, and it matches the vast majority of 0.100" square-pin headers on the market.
The tin-plated posts with 100.0 microinches of tin are the solder-tail finish, suitable for wave or hand soldering without additional plating. The square contact shape is standard for 0.100" headers and ensures a reliable four-point interface with the mating pin.