DESIGNED TO FIT: The rectangle face plate is for use in place of the EWF01 Electrolux Pure Advantage filter, the curved face plate is for use in place of the WF2CB Frigidaire PureSource2 filter. NSF 42 CERTIFIED: Each Tier1 refrigerator filter is tested and certified for materials and structural integrity requirements HIGH EFFICIENCY FILTRATION: Reduces Chlorine Taste & Odor, Rust and Corrosion, Sand Sediment, Silt, and Turbidity for 300 gallons or 6 months, depending on water usage and quality