This combo of 2x20 pin (0.1 spaced) header and socket is for the popular Raspberry GPIO cable. It comes in two parts, a 'pin-through' socket and a male header. The socket straddles the center of a breadboard or perma-proto and then header plugs into the top of the socket. Since IDC cables are so standard, but a royal pain to use with breadboards, this is a good and cheap hack for prototyping
Works best when soldered in place. We have used these to prototype on a solderless breadboard but some customers report their breadboards don't play nice with the shorter pins so your mileage may vary.
Each order comes with one socket and one header. Breadboard, Perma Proto and IDC cable not included!