California Code, Vehicle Code - VEH § 24006

No person shall sell or offer for sale either separately or as a part of the equipment of a new motor vehicle any equipment or device subject to requirements established by the department unless the equipment or device bears thereon the trademark or name and type or model designation under requirements established by the department and is accompanied by any printed instructions which may be required by the department as to the light source to be used with lamps, any particular methods of mounting or adjustment of lamps or other devices, and any other instructions as determined by the department necessary for compliance with this code.