For flush assembly: The ventilation louver's installation dimensions equal the light opening in the wall minus 10 mm (width) x 10 mm (height). With this installation technique, only the flange is visible on the wall. The depth of the ventilation louver is 122 mm including the flange, which is 5 mm. The standard flange width is 55 mm. Flange width can be delivered with widths from 85 mm to flangeless. The ventilation louver can also be delivered with a double flange. With flange at the back, a flange on the duct can be screwed directly onto the ventilation louver. The vent grille's light opening is the width of the ventilation louver minus 80 mm (40 + 40 mm). The height is the height of the ventilation louver minus 135 / 108 mm for the type "B" (40+95 / 68 mm for "B").