The Reverie King Retainer Bar Kit is essential if you are purchasing two bases together to make a Split-King, Split-Cal King or Split-Queen pair.
The standard corner retainer bars that come with the adjustable base will hit each other when used in the middle of the two bed and will not allow the bases to be pushed tightly together. Simply not install the corner retainer bars and install the Retainer Bar Kit instead (See brackets on inside corners where mattresses are together in the picture below).
If installing your new Reverie Adjustable Bases inside an existing wood or metal bed frame, there is the possibility of the outside corner retainer bars to touch the side rails of your frame. You may need to purchase an additional Retainer Bar Kit for the outside corners (See bracket on outside corner in picture below).