Metal-Fab Temp/Guard Galvanized Deluxe Ceiling Support - 6"Dia

I bought this to prevent my dual flue chimney from drawing smoke/fumes from one opening into the other. Even though I crack open a window to supplement an outside air duct that supplies air into our upstairs fireplace, there must still be a low enough pressure in our house to draw air thru the flue for our lower level fireplace (despite the closed lower fireplace damper). This product is well constructed and fit our standard 12x12 flue tile just fine, and our existing chimney cap was wide enough to fit over the edges of the damper and screw back into place under the outside edges of the damper, though just barely. The damper installed easily with the supplied silicone adhesive, and I was careful to follow other reviewers' advise and uncoil the wire before lowering it down the chimney. The 2 wires shown in the photo join together below the photo, so only 1 wire goes down the chimney. One wire lowers the flapper, the other can engage (by pulling harder on the wire) after the flapper i...