This 60ft 300watt roof and gutter de-icing cable helps prevent costly damage from ice dam formation by preventing freezing of un-insulated roof eaves, valleys, gutters and downspouts to allow water to drain freely. CPRH003 For use on inclined, tab-shingle roofs and in downspouts and gutters only. Not for use on metal roofs. Works best with Prime's Roof & Gutter Control, model # CPRH001