N.J. Stat. Ann. § 51:10-4

Containers used where the gas content is sold by package weight must have the tare weight plainly and conspicuously marked on the container or on permanently attached appurtenances, and the net contents plainly and conspicuously marked on the container or on a tag or other type of label firmly attached thereto. Tare weight shall be construed to be the weight of the container, valve and other permanent attachments but does not include the valve-protecting cap.