These draft blockers keep the cold wind and air from rushing into your room while preventing your room air from going up the chimney. These draft blockers have magnets to use with your prefab fireplace or for masonry fireplaces, simply use your fireplace screen to hold it in place. It is best to measure your fireplace opening and get the right size to do the job.
It's made of a new non-woven carbon fiber fabric and is fire resistant. This is a washable material. And it does not absorb odors.