You wouldn't leave a window wide open in the dead of winter, but that's what you're doing if your fireplace flue isn't shutting correctly.
The metal lid of the Lock-Top Chimney Damper closes against a silicone rubber gasket, creating a much tighter seal that the traditional "throat" damper found inside older masonry chimneys.
That seal can save you $150 a year in heating costs, says manufacturer Whitecaps.
The top damper (so named because it sits atop the chimney) is controlled via a small chain that hangs down in the firebox.
The damper also keeps out rain as well as squirrels and other critters that might try to set up housekeeping in your chimney.