With unlined flues, or flue tiles that don't extend high enough above the chimney crown to "catch" the mounting screws of single-flue chimney caps, order a set of our galvanized, 12 ga., bolt -on legs. They fit Gelco and HomeSaver Pro single-flue caps. The legs extend down and out and hold the cap in place on top of the chimney. Installation may not be totally secure in extremely high winds.