That plate is called a threaded wall mount bracket or rod surface mount. It has a place for threaded stock to screw in and then attach the standoff portion. That is on the Gyford Productions / www. standoffsystems.comThey might have use the mounting plate to the cable (wire suspension) system and adapted the standoff back part to go on to it. They do have a wall mount bracket assembly like that back piece that attaches to wall you are showing.