For the ultimate in convenience, flexibility and time saving, Duo-Flip allows you to change both DOT placard legends and ID numbers in seconds to match your commodity. These Duo-Flip 3-Legend Flip Placard System include 4 placard panels in a single frame: Combustible 3, Flammable Liquid 3, Hot and Blank. Self-contained, .032 aluminum alloy placard panels slide over easily on four aluminum hinges. Notches in the aluminum panels allow you to flip numerals without interference. Panels lock in place with four stainless steel pressure fasteners. Duo-Flip's exclusive, deep-formed aluminum frame provides stability and excellent wind protection. Equipped with extra sturdy mounting holes, standard and clipped corner frames fit virtually any type of cargo tank. Duo-Flip 3-Legend Flip Placard Systems for Tankers are sold per each.