D/2 Biological Solution Spray (1 Qt/ 32oz.) Biodegradable cleaner that is PH neutral and contains No Salts, Bleach or Acids. It is highly effective for removing stains caused by biological growth on surfaces including Marble, Granite, Limestone, Masonry, Concrete, Wood, Canvas and Vinyl & Aluminum Siding. It will not damage glass, metal or plants. Safe around wildlife.