MERV 13 Replacement for Lennox 20x25x5 (19.88x24.75x4.38)

A: This filter does NOT replace lennox x6670 , which is 16"x25"x5" and fits the HCC-16-28 air filter holder.....as far as length of time between replacing filters , that would depend on " dirt" in house.....you can replace these once a year ( makes your furnace work harder) every 6 months or as i do every 4 months ( 2 pack a day smoker Merv 13 filter )...hope this helps

A: Yes it is. Perfect fit, and cheaper than manufacturer.
They say 12 months, but I have a pet, and woods , pollen around here.
I always change every 6 months.
Write date on end of filter before you change.