The “M” and “R” numbers issued by U.S. DOT to hazmat packaging providers are registered symbols that substitute for the company’s name and address when marking hazmat packagings with required information. Recently, DOT stopped issuing “R” numbers, although existing “R” numbers remain valid (unless they were individually canceled).
For a connection to DOT’s online list of “M” numbers showing company names and addresses, click here.
For a list of “R” numbers and their registered holders, click here.
For information on how to apply for an M number, click here.