Model # Duct Size Grille Modal We have a large variety of grilles and registers. To find the size you need, here's all you do 41281 10" x 2" 412 Steps 1 B ov pass you're working on new construction, proceed directly to Step 2, # this is a replacement, it 414BL 12x 2 414 out tha old vent cover. 4168L 14x 28° 416 . 610BL 8x4" 810 Measure the opening in your floor, wall or ceiling.