These are female to female jumper wires used in connecting the female header pin of Arduino or any development board to plug in any other development board. They are simple wires that have connector pins at each end allowing them to be used to connect two points to each other. These are typically used with breadboards and other prototyping tools in order to make it easy to change a circuit as needed.
40 strip female to female jumper wire each cable length about 20cm or 8-inch
It is used to interconnect the components of a breadboard or other prototype or test circuit internally or with other equipment or components without soldering.