These premium jumper wires are 3" (75mm) long and come in a
'strip' of 20 (2 pieces of each of ten rainbow colors). They
have 0.1" male 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.
For best results, when plugging these in a line, have the sides
with the 'silver latch bit' sticking out since that side is a
tiny bit wider than 0.1"