16-11-304. Signs. A retail seller of tobacco products, alternative nicotine products, or vapor products shall conspicuously display, at each place on the premises at which tobacco products, alternative nicotine products, or vapor products are displayed and sold, a sign that is to be provided without charge by the department of revenue that states: "Montana law prohibits the sale of tobacco products, alternative nicotine products, and vapor products to persons under 18 years of age."