This set includes a headlight housing, a light bulb, a light transmission element and a 2x4 conducting plate. The light transmission element is transparent yellow plastic and transmits light from the single bulb to the two headlight openings. The bulb is mounted on the side of 1x2 white brick and power can be connected above or below the brick. The black housing matches those supplied with #4565 , it is almost sufficient to convert #4559 but see Working Headlights for #4559 to see what you actually need.