California Code, Vehicle Code - VEH § 29004.5

No recreational vehicle, as described in Section 18010.5 of the Health and Safety Code, designed to be towed, shall be manufactured for sale in this state, sold, offered for sale, leased, or rented unless it is equipped with a safety connection in compliance with Section 29004 with breaking strength which equals or exceeds the gross weight of the towed vehicle. The retail seller, renter, or lessor shall supply instructions to the purchaser, renter, or lessee of such recreational vehicle on proper methods of making the connection between the towed and towing vehicles. Nothing in this section shall, however, require a lessor of a recreational vehicle to supply to the lessee of such vehicle the required instructions if such vehicle is sold to the lessor by a third party and such third party or the agent of the third party delivers possession of the vehicle to the lessee. In such case, such third party shall supply to the lessee the required instructions.