Broan LB36 36N Box Shape Hood Liner for PM250 and PM390 Inserts, 36-Inch Designed to protect the exterior base of a custom hood; fits PM250 and PM390 Power Pack inserts The durable silver paint finish wipes clean easily and the 4" depth provides good capture The "B" or Box liner is designed to fit into 18" deep wood hoods or cabinet bottoms Fits a 36" range hood width; made of 24 gauge CRS