2 in 1 product will clean as well as protect. The specialty drying agent allows the protection to stay on the surface while the cleaning occurs. Designed and safe for all roof seals. Use a brush or microfiber towel to spread, agitate the tough spots, and then wipe clean with a microfiber towel or hose off with water. The before and after results will amaze you. A simple solution to protect your roof and help eliminate black streaks down the side of your RV exterior.