Transparent louver ventilator The Estra is a transparent louver system which is fitted vertically, and is suitable for both daily ventilation and smoke & heat extraction. The Estra’s aesthetic and sleek design means that it really comes into its own in projects featuring substantial amounts of glass. The Estra has thermally separated profile sections, and is available with either single or double glazing. The choice of louvers available includes point-fixed, circumferentially framed and (semi-)structural glazing. Fields of application: atriums, shopping centres, industrial buildings and offices.