The RB101 is a SINGLE cold shoe attachment that can be mounted to the Riggy receptacles located on either the top or side of the Riggy-Micro series of preamps (not for the Riggy-Assist series of preamps).
The Riggy-Micro preamps are so small and light, they can even be mounted to the camera's hot-shoe by using a hot-shoe to 1/4-20 adapter. Now, you don't need to have the preamp mounted to the bottom of the camera anymore, and you can hand-hold and cradle the camera like a real DSLR. Since the preamp is occupying valuable real estate on the camera in this position, we designed the RB101 Riggy Cold Shoe Attachment, which adds a cold shoe attachment to the enclosure of the Riggy-Micro. The Riggy-Micro has facilities for mounting two separate RB101 Riggy Cold Shoe Attachment; one on the top, and another on the right side.
For a comlete kit for mounting the Riggy-Micro to your hot-shoe, please see the RB200 Riggy Cold Shoe Top Mounting Kit. This includes 2 RB101 cold shoes, plus the adapter necessary for mounting to the camera cold shoe, plus hardware to secure the unused camera mouning screw.