This is a 8-pin female header, with extra long legs that are slightly offset. The offset helps correct for the weird 0.16″ spacing between the two 8-pin headers on the digital side of an Arduino. Stick this and an 8-pin Stackable Header on an Arduino and D7 and D8 pins will be spaced by a more standard 0.2″. This allows you to then use a standard perf board stacked on top of the Arduino.
Pins are spaced by 0.1″.