GUARDIAN generates heat when it contacts ice. The spherical shape of the pellets results in the immediate melting of ice and snow. The pellets bore down into the ice and snow, melting it as its interface with the surface, allowing for fast easy removal. The resulting slush and water should be removed to help eliminate refreezing. There should not be refreezing, even at zero degrees, for about 12 hours. Calcium Chloride is the most effective deicer being sold today. GUARDIAN is effective well below zero degrees in melting ice and snow. This product does not leave a white residue and will not cause browning of grasses and shrubbery when used as directed.