Accord ABRFWH2020 Return Filter Grille with 1/2-Inch Fin Louvered, 20-Inch x 20-Inch(Duct Opening Measurements), White,Accord,ABRFWH2020" /> Steel construction, 1/2-in spaced fins For sidewall or ceiling application Removable hinged face accepts nominal 1-in thick filters for easy installation and cleaning The number of louvered columns and mounting holes will vary based on the size of the grille ordered Listed product sizes refer to the duct opening measurements, not the register itself