Z-Stop with Nails is a roof moss, algae & fungus inhibitor that is applied in strips to old or new roofs. It works with any wood or composition roof and lasts 20 plus years. Easy to install, completely safe for roofing singles and works on any roofing material made of composition, flat tile, metal, shingles or cedar shakes. An ideal product for both the do-it-yourselfer & the professional roofer. Made from 99.2% Pure Zinc.