... -20m Hole diameter:0.8mm-20mm Material:ss sheet,GI. High quality perforated metal mesh ( factory & ISO9001:2000)perforated metal mesh ... brass plate, aluminum plate, nickel plate and kinds of nonmetal plates.Hole of perforated metal mesh: round, length, square, scale hole ... generator room, factories, and other noise sources in acoustic noise with sound-absorbing panels that can be used in the building ...