This is a green colored 40 Pin 2.54 mm(0.1") Single Row Pin Header Strip from DFRobot. These 0.1" header strips are commonly used as low-cost Arduino connectors. The standard spacing allows use with solderless breadboards, perforated prototyping PCBs, and female headers such as those used on our Romeo robot controllers. These header strips can easily be snapped into smaller strips to fit your application.
These colored pin headers will help you label pin rails depending on their function.
We commonly use:
Green for digital I/O
Blue for Analog I/O
Red for Voltage