The Leofoto DC-22 Mini Clamp is a compact adapter that can be used to mount accessories on compatible camera cages and various other camera supports. It features a shoe mount, a 1/4"-20 mounting thread, and an Arca-Swiss dovetail clamp that's secured by a knob.
A common scenario is attaching it to a cage that has a built-in Arca dovetail. Attach it this way via the Arca clamp, and then attach an accessory to the shoe mount or 1/4"-20 thread, an accessory such as an articulating arm. Another example is attaching it via the 1/4"-20 thread to a matching 1/4"-20 screw on a monopod or selfie stick, and then mounting a compatible cage or something else onto the Arca clamp.