Milk shakes, malted milks, or malts, as such terms are commonly used in the restaurant, confectionary, or soft drink trade shall not be made from imitation ice cream or imitation ice milk or served to any customer for consumption upon the premises where they are made unless there is displayed upon such premises and visible to all customers a sign, which, as the case may require, shall read: “Imitation ice cream used in the milk drinks served here” or “Imitation ice milk used in the milk drinks served here.”

Each such sign shall be printed in plain block letters not less than six inches high.