NFPA Adhesive Label Kit (Placard, Digits & Symbols) By SmartSign | 12" Square 3M Engineer Grade Reflective NFPA diamond, when measured from the top to bottom of the diamond, is actually 17" high (eg which is the same as the 12" square tilted by 45 degrees) Digits are self-aligning Your NFPA Kit is a snap to assemble