Double Wall Spiral Pipe with Galvanized 5.394″ Slit Coil, Unfaced Liner and 5.394″ 22 Gauge Perforated Inner Section.
For Double Wall Round or Rectangular Duct, a Perforated Inner wall provides better sound attenuation than a solid inner wall; Unfaced Liner provides better sound attenuation than standard Duct Liner with a mat facing although for Double Wall jobs in which thermal specs are primary focus, either unfaced or faced (standard Duct Liner) is acceptable
