AEROVAC® Series CEAL format louvres are suitable for intake or exhaust systems where space or cost is at a premium. The Aluminium Exhaust and Fresh Air Louvers are used both internally and externally in buildings for the extraction of re - cycled air, intake of external fresh air of the expulsion of contaminated air. The quality of the material used and the particular inclination of the blades at 45° angle downward offer a weather resistant.