Steyregg ventilation-technology and metal-fabrication group, founded around 1965 and employing more than 200 people across Steyregg and Vienna, holding two live VKF recognitions in Untergruppe 504 Brandschutzklappen — 40673 and 40674, both issued in the current numbering block. A fire damper is what stops a ventilation duct from carrying fire and smoke through the compartment wall it passes, and Aumayr is the only Austrian holder of that approval in the register. Its own site publishes ISO certification since 1995 and the Austria Gütezeichen but no damper certificate numbers, so the VKF recognitions are the quotable evidence.