White polyester powder coated ceiling diffusers with damper.
Sizes listed in drop down menu are the duct size/neck size. Add 145mm for overall size and 100mm for ceiling opening size. For example a 300x300 diffuser will require a 300x300 grille box, a 400x400 hole in ceiling and will cover 445x445 overall. For a standard suspended ceiling tile replacement you will require a 450x450 diffuser (595x595 overall).