Cal. Bus. & Prof. Code § 17050
The prohibitions of this chapter against locality discriminations, sales below cost, and loss leaders do not apply to any sale made:
(e) In an endeavor made in good faith by a manufacturer, selling an article or product of his own manufacture, in a transaction and sale to a wholesaler or retailer for resale to meet the legal prices of a competitor selling the same or a similar or comparable article or product, in the same locality or trade area and in the ordinary channels of trade.
The notice required to be given under this section shall not be sufficient unless the subject of such sales is kept separate from other stocks and clearly and legibly marked with the reason for such sales, and any advertisement of such goods must indicate the same facts and the number of items to be sold.