The Dometic Air Distribution Box attaches to the A/C and equally distributes the air filling up your mobile living space with cool air. If roof thickness is greater than 4" then the Dometic Bolt Kit would need to be purchased.
Universal ADB Model on label
3314854.000 Scope of delivery
ADB, Installation and operating Manual, Installation Material Product Description
Air Distribution Box - For use with Brisk Air II High Efficiency model B59530 only - Manual ceiling controls.