Broan 509 Through-Wall Fan, 180 CFM 6.5 Sones, White Square Plastic Grille PLASTIC Imported Broan 509 through-wall fan 180 CFM 6.5 sones 8-3/8-Inch diameter sleeve Specially designed polymeric fan blade Housing adjusts to fit walls from 4 1/2-Inch to 9 1/2-Inch thick Built-in damper minimizes back drafts 180 CFM 6.5 Sones 8 3/8-Inch diameter sleeve Specially designed polymeric fan blade Housing adjusts to fit walls from 4 1/2-Inch to 9 1/2-Inch thick Built-in damper minimizes back drafts