N.J. Stat. § 51:10-2
Liquefied petroleum gas shall be sold or offered for sale by avoirdupois net weight, by liquid measure based on the standard United States gallon of two hundred and thirty-one cubic inches, or by cubic feet based on the standard cubic foot of one thousand seven hundred and twenty-eight cubic inches; provided, however, that nothing herein shall be interpreted so as to prohibit the sale of such product by other units heretofore employed by industry and accepted by the trade and approved by the superintendent of the division of weights and measures of the Department of Law and Public Safety, if the scale or meter used to determine weight or measurement and the invoice rendered clearly indicate to the consumer the equivalent of such unit in avoirdupois pounds, United States standard gallons or cubic feet and fractions thereof.
N.J.S. § 51:10-2