12.5x20x.38 (12.44x19.75x.38) Honeywell Replacement Pre-filter
Honeywell washable electronic pre-filter for 12 1/2 x 20 models F50A, F50E, and F50F (Two 12 1/2 x 20 filters replaces one 20x25 filter). Nominal size is 12 1/2 x 20 x 3/8. Actual size is 12 1/2 x 19 3/4 x 3/8. Use two 12 1/2 x 20 filters to replace one 20x25 filter! Honeywell pre-filters capture large particles to extend the life of your filter.