Similar to our Mission Style Sign Blanks, the Dome-Top Sign Blanks have a square shape with a rounded top. They are made from cellular PVC, a top-quality material that will never rot and resists the effects of heat, cold, and sun. Count on a PVC sign blank to survive exposure to the elements. This sign blank measures 18" wide and 18" high. Choose your thickness and edge style: 1/4" square edge, 1/2" square edge, 1" square edge, or 1" bullnose edge.