Roof and gutter De-Icing cables help prevent costly damage from ice Dam formation by preventing freezing of un-insulated roof eaves, Valleys, gutters and downspouts, and allows water to drain freely. This product is for use on inclined, tab-shingle roofs and in downspouts and gutters only. To ensure water can flow to the ground, cable should be installed on Unheated portions of the roof (usually the overhang) as well as in Valleys, gutter and downspouts. Roof and gutter De-Icing kits are available in lengths from 30 ft to 240 ft. These products are found as De-Icing and snow melting sets primarily in northern markets beginning in early October.