Stuf-fit is a mesh made out of copper and will not rust as will steel wool. The uses you find for this product will amaze you. Fill up small holes and cracks, and if you use some kind of sealer with the stuf-fit this will make the seal much stronger and if any rodents try chewing into the stuf-fit, they will not like the way that the mesh feels in their mouth and will go away.
ALWAYS READ AND FOLLOW THE LABEL FOR SAFETY AND BEST RESULTS