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LRCNA is a sound attenuator for ventilation systems. The main material of these silencers is galvanized steel (Z275) and glass wool delivered in flocks. Straight sound attenuator with circular connection and low installation height. LRCNA dimensions makes it particularly suitable for residential ventilation, installation above suspended ceilings, or where space is otherwise limited. The space between the inner and outer ducts is filled with blown flocks of glass wool and the inner duct is covered with a nonwoven cloth to prevent fibres from getting into the duct system.