Size
Primary source
Verbatim text below is from the Electronic Code of Federal Regulations (eCFR), a public-domain U.S. government work. Always verify the current version with the eCFR before relying on it for any legal matter.
Full Text
Size may be specified in connection with a grade by agreement between buyer and seller and stated in terms of minimum diameter or minimum and maximum diameters. Diameters shall be specified in inches and not less than eighth-inch fractions thereof. In addition, size may be stated in terms of ratio of length to diameter.
This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.