Set of 2 Wet and Forget Moss, Mildew and Algae Stain Remover Set of Two (0.75 gallon) Concentrate bottles that make over 4.5 gallons each Cleans exterior surfaces with no pressure washing or scrubbing required Non caustic, non acidic and no bleach Coverage: 550 - 1,700sq feet depending on porosity and amount of staining Apply with pump up garden sprayer