Rather than pay three times as much for a multi-step kit that can take up to an hour of work per headlight, I opted for this inexpensive and simple alternative.  Not only did it WORK on my sister's 2007 Corolla's 100,000 mile, VERY yellowed and foggy headlight covers, it worked in just FIVE MINUTES PER COVER!  And I used only 1/3rd of the 10oz bottle!  So my cost was $2 and time was ten minutes.  The covers went from under 50% light transmission to at least 90%.  With the lights on at night, standing in front of the car, you can still see a bit off fogginess, but when driving the lights work great!