This is an accessory for the IMS conversion system on a RED ONE MX camera.
I don't know much about these other mounts, other than I don't need this particular component.
If you have the kit installed and need this mount, this could be the part you need.
I am happy to accept any more information about the item if I've made any mistakes in my description.
Only what is picture is included.
I have a BNCR mount from this kit for sale also. And an original RED PL.