Lilly Miller® 100503874 Moss Out For Roofs & Walks Concentrate, 27 OzKills moss quickly see results in hours. Non staining formula can be used on roofs, walks, decks and patios. Does not stain concrete, pavement, stucco, or wood. Economical concentrate. Active Ingredient: Ammonium soaps of fatty acids. Liquid concentrate destroys moss on roofs, patios and sidewalks without staining. Adds months or years of life to roofs. Eliminate dangerous moss from concrete and wooden walks, decks and steps without staining.