Package of commercial grade prefilters for F300 or F50F electronic air cleaners. Two of these prefilters are used in Honeywell 16-inch x 25-inch F50F or F300 air cleaners. Prefilters generally do not wear out but replacement may be needed over time as woven aluminum foil corrodes. Fits F300E1019, F300A1625 and F50F1073 model air cleaners. This prefilter will not fit F50A or F50E series.