3M Fire Barrier Moldable Putty Stix MP, 1.45 in x 6 in

I use this for blocking holes in engine firewalls. It molds easily around cables and wires and sticks well to block the holes. I have not checked its fire resistance. After a year it is still flexible and stuck in place. Does the job of blocking fumes from making their way out of the engine compartment.

This is the Ul/CSA certified stuff that works! I was rebuilding a Suburban RV furnace and needed a fire/heat certified putty to replace the 30 year old stuff used to seal the fuel gas supply line between the heat exchanger and blower enclosure. This is a fire safety item and I did not want to trust the foreign-sourced material. I was delighted to find this 3M product here on AMZ. Genuine 3M quality sticky stuff that seals perfectly and likely to endure another 30 years. I had to look up the word 'intumescent' lol. Oh, yeah, just what is needed.

I needed something to block openings around the electrical boxes for lights and smoke detectors in my ceiling, and this is a much better option than only using caulk (at least in areas where the red color doesn't show). I'm impressed with how easy it is to mold into the right shape with its putty consistency - as well as its ability to be stuffed into odd shaped openings. The fire retardant capability is a great plus

Very workable and hopefully flame proof putty. Easy to work with and good to put a temporary seal around air drafts.

I've been using 3M fire barrier for 30 plus years. As a requirement under the National Fire Protection Association, it is a requirement when running telecommunications cables through firewalls. Every now and then, I pick up a project that requires me to use this. It is most always readily available, and the price is competitive with other manufacturers. It is also moldable to any form. In my opinion, this is the best fire barrier on the market.