NFPA Diamond Signs make sure that your chemicals are well known. Increase safety around chemicals that are highly hazardous to your health, with an NFPA sign.; This sign is often used for Carbon Dioxide, Helium, Neon, Nitrogen Gas and Sulfur Dioxide. Sign is made from adhesive vinyl for lasting durability. This NFPA sign measures 14" tip-to-tip (but when you measure the sign as a square, they are 10" long on each dimension). Each number is about 3" high - which using common visibility benchmarks, should be legible from 100-150' away. This gives firefighters plenty of time (and space) to safely gauge their proper response to an emergency, spill or fire.