Handy for making wire harnesses or jumpering between headers on PCB’s. They have 0.1″ sockets on either end and fit cleanly next to each other on standard-pitch 0.1″ (2.54mm) header.
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″
Note: Retail price per piece.
This product and description is from Adafruit.