These headers are made to work with the Arduino Main Board, Arduino Pro, and the Arduino Mega. They have longer contact length for clearing the USB-B connector and great for stacking multiple shields. This kit includes 4 headers (2 8-pin and 2 6-pin), enough to connect a shield to an Arduino Main Board. This Kit is consist of 2 1x6 Stackable Header For Arduino Shield and 2 1x8 Stackable Header For Arduino Shield