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.   Note: You will have to click on the “In This Article” box and drop down to click on “Manufacturers’ Symbols”.

For a list of “R” numbers and their registered holders, simply  click here.

For information on how to apply for an M number, click here.

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