NEW IN 2018! Our VIPER ROOF ROLL™ is your premium, NON CORROSIVE, solution in preventing ice dam's this winter. Our Viper Roof Roll prevention option includes four rolls (approximately 21 inches long) that contain calcium magnesium acetate. Place the Viper Roof Rolls 12-24 inches above your downspouts or where you generally have ice build up through the winter months. The time released roof roll will release CMA and work from the bottom up so that ice doesn't adhere to the surface creating an ice dam or buildup. Calcium magnesium acetate is chloride and salt free and will not harm roof components. It is less corrosive than water and any runoff onto vegetation or new concrete is harmless. Pet friendly. Easy installation.