Blocks old, unused thimble holes in masonry chimneys.
Provides a thermal break from combustibles and prevents downdrafts
from entering the room.
Constructed of a ceramic based fireproof insulating
material. The black outside plate covers up to a 10" diameter
Installs easily, simply insert the plug into the
old thimble opening and tighten the expansion screw on the face
of the plug. The side expand and create a tight fit inside the
thimble opening. To remove simply reverse the process.