Wow!  This stuff is great.  Put it on, let it dry to a haze, rub it off.  Cleaner and clearer headlights.  Not as perfect as new, but much better than the ugly, yellowish hue that was present before I used this product.  You do not need any sandpaper products or rough matter to sand the headlights first.  Just apply like you would car wax and rub it off when it's in the hazy state.  A little elbow grease will produce a better result.  And if you desire and you have the equipment to do so, then a drill and a buffing pad will make the job a bit easier and the end result will be a wee bit better than just rubbing with your hands.  But...  you don't need to run out and buy a drill or buffing pad and attachment.  Rubbing vigorously with your hands will produce some amazing results.