Visual and audio warning apparatus, namely, electrical warning lights and acoustic alarms; signalling apparatus and instruments, namely, transmitters and receivers of electronic signals; sirens and alarms; beacons, namely, luminous beacons; lenses for lamps, namely, lenses specifically adapted for electric warning lights in the nature of lamps, for use in vehicle emergencies; electric signs, road signs, luminous or mechanical, and electronic display boards; hazard lights, namely, flashing saf...