Amdro PowerFlex Weed & Grass Killer System Sprayer w/ Free 4 oz Concentrated Cartridge AMDRO PowerFlex Weed and Grass Killer concentrate is formulated to kill weeds and grasses down to the root. For use only with the AMDRO PowerFlex ready-to-use cartridge sprayer. Insert the cartridge into the top of the sprayer to kill weeds and grasses. Kills weeds and grasses down to the root Starts to work immediately Each 4 oz. cartridge makes 1 gal. of weed and grass killer For use with AMDRO powerflex ready-to-use cartridge sprayer only