Used to connect two Picatinny rails together, allowing you to create the unholiest of customs. Get one if you're attaching something light, but you'll probably need two for extra rigidity. The exposure of the hardware is minimized with this particular design. Not meant for "real" applications.
I used M5 x 0.8 screws and nuts for the hardware.
The bar in the center is to keep the pieces from getting lost during manufacture. You will need to cut/trim this off.
Tested in Strong & Flexible White.