This ventilation grille allows the air introduction or extraction between one room and the outside. It is made of 0.6 millimetre thick aluminium. Available in natural aluminium finish. Available in various sizes (10 x 10; 15 x 15; 17 x 17; 20 x 20; 25 x 25; and 30 x 30 centímetres). Available with an air passage from 25 square centimetres, for the smaller model, to 240 square metres for the bigger ones. It is supplied in pack or in a single unit.