I installed these on the stackable units.  One side screwed into the top unit and the other sided anchored into the wall.  I did the same on the bottom unit.  All as shown in their pictures and as directed.  For the top shelf and rod, it is so high that I have to get on my toes to reach (I'm 5'4").  The bottom shelf and rod obviously is reachable but the shirts from the top rod hang right down on top of the shelf so that the shelf is basically unusable.  It looks nice and everything is organized though.