The National Marker Company sign with the legend ?FIRE DOOR - DO NOT BLOCK? is commonly used in commercial and residential buildings to inform not to block the indicated fire door. This fire safety sign uses contrasting colors to easily garner attention and helps in enforcing fire safety regulations. The use of clear, bold font makes sure the sign is easily readable in most lighting conditions and even from a distance. The signage has an NMC Sign Muscle coating to protect the text against fading, scratches, scuffing, mold, and moisture.