Egg crate grilles have long been used for extract purposes. The lightweight aluminium lattice results in a large free area (approx. 90%), making them ideal for high air volumes with minimal noise and pressure loss.
The damper fitted to the rear of the grille allows for volume control and can be adjusted using a screwdriver on the worm screw located through the front face and to one corner. Typically a clockwise turn will open the damper.
Note that the stated sizes are nominal and refer to duct/aperture size. For overall size (including the flange) add 45mm.