The Helios ELF-ALB 50/30 G4 is a set of high-quality replacement filters for ALB fresh air boxes. Each filter is made from durable synthetic filter fleece and encased in a fiberglass frame to ensure stability and effective performance. Tested according to DIN EN ISO 16890, these filters are rated ISO Coarse 90% (G4), providing efficient capture of large dust particles and debris. Supplied in a pack of three, the ELF-ALB 50/30 G4 filters are designed to maintain optimal airflow and protect ventilation systems in residential or commercial settings.