These female-female premium jumper wires are handy for making wire harnesses or jumpering between headers on PCB's. They're 3" (75mm) long and come in a 'strip' of 20 (2 pieces of each of ten rainbow colors). They have 0.1" female header contacts on either end and fit cleanly next to each other on standard-pitch 0.1" (2.54mm) header. The best part is they come in a 20-pin ribbon cable. You can always pull the ribbon wires off to make individual jumpers, or keep them together to make neatly organized wire harnesses.
Note: The length of the jumper wires is sometimes a bit longer than what is listed.
For best results, when plugging these into a male header, have the sides with the 'silver latch bit' sticking out since that side is a tiny bit wider than 0.1".