Brasso is a metal polish, but it is not restricted to use on wheels. Brasso polish will remove fine scratches-like those found on old headlights. Over time, many vehicle headlights develop a "haze" on them from years of being exposed to the sun and other elements. If you want to restore the lights to their original clarity, you'll need to buff out those scratches.
Apply the Brasso to the lens of the headlight assembly.
Work the Brasso into the headlights with an orbital buffer. Start out wiping the Brasso across the headlight with the power off. Then, turn the power onto the lowest setting and allow the buffer to do the work. The Brasso will polish the headlight lens and remove the haze very quickly.
Wipe the headlight lens with a clean, lint-free towel.