i was skeptical of this when my wife suggested it. i told her roofs were suppose to do this after time. i went to Menards to purchase a product and tried it in a small area ( no results) we went ahead and had it done and our roof looks like the day we had it installed. this is the best money we have spent to keep the house looking like the day we built it. GREAT JOB!!! I would recommend this to anyone.