This article does not apply to materials which are of a class or kind which are not, or which are manufactured from materials which are not, produced in the United States, nor to key-driven calculators manufactured in branch plants located outside continental United States, but which plants are wholly owned and operated by a corporation the majority of whose stock is owned or controlled by an American manufacturer whose principal manufacturing centers and home offices are located in the United States.
Ca. Gov. Code § 4301