Roundup 5705010 Extended Control Weed and Grass Killer Plus Weed Preventer Concentrate, 32-Ounce Dual-action formula kills existing weeds and prevents new ones from growing for up to 4 months Kills weeds to the root. Guaranteed!* *Consumer Guarantee: If for any reason you are not satisfied after using this product, simply send us original proof of purchase and we will refund the purchase price. Use on driveways, sidewalks, and patios; along fences, foundations, curbs, retaining walls and edge of lawns, as well as on decorative rock or gravel areas Rainproof in 30 minutes Visible results in 6 hours