California Code, Vehicle Code - VEH § 24005

It is unlawful for any person to sell, offer for sale, lease, install, or replace, either for himself or as the agent or employee of another, or through such agent or employee, any glass, lighting equipment, signal devices, brakes, vacuum or pressure hose, muffler, exhaust, or any kind of equipment whatsoever for use, or with knowledge that any such equipment is intended for eventual use, in any vehicle, that is not in conformity with this code or regulations made thereunder.