Placards that display safety signs, advertisements or safety slogans including "Drive Safely" or "Drive Carefully" may not be affixed or displayed on packagings, freight containers, unit load devices, motor vehicles or rail cars after October 1, 2001. HM-206, a final rule that made several changes to the Hazardous Materials Regulation, contained a four-year transition period for those flip-top metal placards that were permanently attached to transport units (as long as they were installed prior to August 21, 1997). See 49 CFR Part 172.502(b)(3).