Insul-Plug Black Masonry Chimney Thimble Hole Plug - 8-Inch DiameterDon't let old and unused thimble holes affect the efficiency of your masonry chimney. Use Insul-Plug Black Masonry Chimney Thimble Hole Plugs to seal any holes spanning up to ten inches in diameter.

- Blocks unused thimble holes in masonry chimneys
- Made with completely fireproof materials
- Plate covers 10" hole
- Fits 7.75" to 8 1/8" diameter opening
|  | 
  |  |