California Code, Business and Professions Code - BPC § 17533.9

It shall be unlawful for any person, firm, corporation, or association, in any newspaper, magazine, circular, form letter, or open publication, published, distributed, or circulated in this state, including over the Internet, or on any billboard, card, label, or other advertising medium, or by means of any other advertising device, to advertise the sale of tear gas, tear gas devices, and tear gas weapons, as defined in Sections 17240 and 17250 of the Penal Code, unless there is conspicuously displayed or stated in connection with the name and description of that tear gas, or those tear gas weapons or devices, a direct and unequivocal statement that will clearly indicate that possession or transportation of tear gas and tear gas weapons or devices is prohibited by law unless specifically exempted or permitted pursuant to the authority contained in Division 11 (commencing with Section 22810) of Title 3 of Part 6 of the Penal Code.