Wet & Forget Xtreme Reach Hose End Outdoor Cleaner with additional Refill, the nozzle attaches to garden hose; jet tip sprays up to 30ft to remove green and black stains caused by moss, mold, mildew, and algae on roofs and 2nd story siding; fan tip provides quick application to large surfaces driveways, patios and decks; no scrubbing, no rinsing, and no pressure washing, just wet it and forget it | Spray dry surface on a cool day to avoid rapid evaporation of product, do not rinse, apply when rain is not forecasted within 4-5 hours, apply when the temperature is above 55° F | Cleans over time with the wind and rain, green stains clean up within 1-2 weeks, black stains or heavy, stubborn stains can take several months, long-established stains may take 6-12 months; surfaces can stay clean up to 1 year or longer | It is bleach free and non-acidic; spray 100 feet away from lakes, ponds, rivers, and streams and flush plants with water before and after application | Includes 2, 48 Fl. Oz bottles, one with nozzle, one refill, each bottle has an unlimited shelf life and treats up to 2,000 square feet, heavy stained and porous surfaces will absorb more product