Redrock Micro's ultraCage Black BMCC Deluxe Cage Upgrade Kit is specifically for use with an ultraCage Black for the Blackmagic Camera. Three components make up the kit: a top handle to attach to the very top of the cage, either pointing forward or backward, and an ultraPlate and a connection component that together secure the camera to right underneath the top of the cage.
The connection component attaches to right underneath the top of the cage, and the ultraPlate, which is a mini cheese plate with 1/4" threads and a cold shoe, attaches to the top of the camera. By means of its cold shoe, the ultraPlate, along with the camera attached to it, slides onto the connection component to firmly secure the camera to the cage. If you ever remove the camera from the cage, you'll certainly be able to use both the threads and cold shoe of the ultraPlate, which you can at all times keep attached to the camera.