Chimney 34200 6 Inch Insul-plug Blocks Unused Thimble Holes In Masonry Chimneys

The Insul-Plug blocks old, unused thimble holes in masonry chimneys. It provides a thermal break from combustibles and prevents downdrafts from entering the room. The Insul-Plug is constructed of a ceramic based fireproof insulating material. The black outside plate covers up to a 10″ diameter hole. Simply insert it in the old thimble opening and tighten the expansion screw on the face of the Insul-Plug. The sides expand and create a tight fit inside the thimble opening. It can be removed by reversing the process. Features: Type: Insul-Plug. Specifications: Overall Dimensions: 6″ (W). Adjustable: 5 3/4″ to 6 1/8″.