The Difference Mirafi ® FW-Series Engineered Filtration Geotextiles Make, Engineered Filtration. Resists clogging while maintaining flow rates in high gradient and dynamic flow conditions. Durability. High survivability rating in aggressive installation and loading conditions along with excellent resistance to chemicals in aggressive environments. Soil Interaction. Superior soil confinement resulting in greater load distribution. Unique Constructions. Manufactured with highly UV stabilized multifilament fibers which provide uniform opening size (AOS) while maintaining high long-term flow rates