Roundup Dual Action Weed & Grass Killer Refill, 1.25 gal. features a powerful dual action formula that effectively kills existing weeds and grasses down to their roots. It also prevents new weeds from growing for up to four months by creating an invisible barrier in the soil. This refill is for use on driveways, sidewalks, patios, around trees, landscaping areas, along fences, and gravel areas. For optimal results, apply during warm, sunny weather above 60 degrees Fahrenheit. It becomes rainproof in just 30 minutes and delivers visible results within six hours. Model Number: