Pair of vertical rails mounted to the left and right side of a recessed on the face of the wall. Frame hangs onto these rails placing weight of frame on the wall.
With a TV recessed into an opening, just mount the two vertical metal rails onto the left and right side of the face of the recessed opening in the wall. Then the hooks pre-installed on the back of the frame attach the frame directly to these vertical rails supporting the entire weight of the frame by the wall. The side view of this install provides for a tight install to the wall.