We offer two varieties of engraved fire door signs - indoor engraved and outdoor engraved. Made of 60 mil thick plastic with precision-engraved characters on a smooth acrylic plate, the indoor engraved signs are designed to last at least 5 years outside.  The outdoor engraved signs are also 60 mil thick, but the print is engraved onto textured, weather-resistant plastic. These signs are more durable and promise an outdoor life of at least 15 years.