These two Short Female Headers alone are, well, lonely. But pair them with any Adafruit Feather boards and you're in business!
These headers are particularly cute and tiny with a body height of just 5.0 mm they are the best way to minimize the amount of space your Feather project takes up, but still maintain that flexible configuration. "Normal" socket headers have an 8.5mm body height so this saves you a whole 3.5mm (hey it adds up!). You can use the male headers that come with your Feathers, but you may need to cut the male headers on your Featherwings down by a few mm, so just be aware of that!
What do they do? They get soldered on either side of the Feather board. Now you can plug in FeatherWings to add more capability to your portable project.
Note: Comes with one 12-pin and one 16-pin header, Feathers not included