The sleeve (outer part, shown in black) is removable from the backplate (inner part, aluminum) making it easy to insert the rod from above, below, or any direction.
Important: Socket backplates are 3/8" thick. If using a socket on both ends of a straight rod, be sure to subtract 7/8" from the overall width of the opening. This gives room for the backplates plus 1/8" of wiggle room. (3/8" + 3/8" + 1/8" = 7/8").