The Helios ELF-ALB 80/50 G4 is a fully synthetic replacement filter for ALB fresh air boxes. It features synthetic filter fleece combined with a sturdy fiberplast frame to deliver effective filtration. Tested under DIN EN ISO 16890 standards, this filter is rated ISO Coarse 90%, equivalent to filter class F4. It ensures dependable filtration to support optimal air quality in Helios ventilation systems.