copper mesh is a 99.99% copper wire mesh exclusion material that is used as a physical barrier to block birds and rodents from entering openings and tight spaces. Rust-Proof and stain-proof, copper mesh works best when packed tightly into holes or cracks less than 3 Inch in diameter. Copper mesh is ideal for use in eaves, roof tiles, retractable awnings, behind signs, where pipes enter siding and foundation, cracks, holes, or any small openings that need to be filled to keep mice, rats and pest birds out and is easy to cut with scissors. Can be used in conjunction with professional foam.