Z-STOP is a zinc moss, algae and fungus inhibitor that is applied in strips to old or new roofs. It works with any wood, flat tile, metal or composition roof. The natural action of rain water time-releases zinc carbonate, a proven fungistat, which then washes down the roof preventing destructive moss, algae and fungus growth. Z-STOP is an ideal product for both the Do-It-Yourselfer and the professional roofer.