3M Fire Block Sealant FB 136, Gray Color, Single Component, High Temperature and Smoke Passage Resistant, 10.1 fl oz Cartridge

I used this to fill in the electrical hole and floor anchor holes. The product is as described. Seals great and eliminated air flow. Easy to apply and fills in very well. Don’t get this stuff where you don’t want it, can be difficult to clean. Once dryer the plastic caps in the safe were secured and don’t pop out. Extremely durable. Can be cut with a razor blade to add a nice finished look.

I used this to apply a rope gasket to an outdoor stove as it cost much less than others. It worked very well.

Never used this product before. Had to fix a few cracks around the chimney from the vent pipes. Was really easy to spread as needed easy clean up. Really matched the cider blocks. I will be using it again if I run into the same problems.

It done the job so far

I bought this to seal up a stove vent where it exits the siding. It does a great job sealing and protecting siding from heat

Used it to seal around ceiling light electrical box. Was kind of runny at first but did the job.

Doesn't stick nor will it hold up to the heat. At 400 degrees it becomes very brittle and falls off.

I’m really hopeful this product works as advertised if only because it has no business in a caulking gun and I never want to have to use it again. Used it to close some gaps in our fireplace masonry, but it’s more like spreadable putty than caulking. I nearly broke both arms trying to dispense 2 tubes of it, even after hitting the “F it” button and cutting the tip so wide, it should have been easily dispensed. Any harder, and I’d have been breaking out woodworking clamps to squeeze the caulking gun handle.