The RSIC Smart Leveling Clip is for ceilings, or walls. It can be attached to both CMU, Steel, Wood, or Concrete wall or ceiling systems. The clip has up to a 1 inch of adjustment available, allowing you to true a wall or ceiling. Usually only one side of a CMU or Concrete wall gets a good true line. The Leveling Clip will cover up the imperfections on the other side. It also allows for a mechanical chase between the CMU or Concrete wall, for electrical conduit and water service lines.