The board can be used to join cables with 4-pin SH JST (and compatible) plugs, commonly used by STEMMA QT / Qwiic ports on microcontrollers and add-on boards.
These are handy for extending a Qwiic cable if you don't have one long enough for your project, or to protect a port if you're regularly swapping out sensors/dev boards. The pin connections are 1-1, matching both sides.
The pack includes four boards.