The wall louvres type MLSN-SLS and NKV-G offer economic methods for the provision of air inlet into buildings. The systems are suitable for industrial or commercial buildings where ventilation is required. The lightweight construction allows the production of a wide range of products, which can be installed to meet almost any Engineering or Architectural requirement. The aerodynamically shaped extruded aluminium profiles of the MLSN and SLS can be used to create continuous panels of fixed or operable wall louvres. An internal mullion system allows for a “Click Fix” blade installation process with no external fixings to spoil the Architectural appearance, whilst ensuring full blade support and alignment. The operable louvres have internal damper sections, which provide for volume control without any ovement of the external blades. The NKV-G louvres are formed from high quality aluminium or stainless steel sheet, with profiles designed to provide a strong louvre blade with maximum protection against rain penetration. The operable louvres have alternate fixed and operable blades, so that in the open or closed positions the outer blade remains in a fixed position. A wide range of ancillary fittings from stainless steel bird guards to bolt on sound reduction attenuators is available and a wide range of controls enable the louvres to open exactly at the right opening angle based on all weather conditions. Fixed blade continuous louvres may also be used for Architectural screening purposes.