Roundup Extended Control Weed and Grass Killer Plus Weed Preventer II Ready-to-Use Pump 'N Go Sprayer, 1.33 Gallon Dual-action formula kills existing weeds and prevents new ones from growing for up to 4 months Rain proof in 10 minutes Visible results in 3 hours 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 Kills the Root - Guaranteed!