Hazard Class 4 Spontaneously Combustible Worded Placards are required by 49 CFR 172.500 for highway, rail and water shipments of hazardous gases. Designed to meet DOT specifications for color and size, these 273mm x 273mm Spontaneously Combustible Hazard Class 4 Placards may be used domestically as well as internationally. Our DOT placards are printed with durable UV inks that retard peeling, chipping and fading. Sold in packs of 25. Also sold in cases. Case quantity based on material.