Trane Perfect Fit BAYFTAH23M2 23.5x21x5 Air Filter

Looks good. Arrived OK. Keeping it as a spare, will order another when changed. How long should this size filter be used before replacement? Thanks.

I bought these to replace the ones I previously purchased from Atomic about a year ago. I haven't even opened this package yet, but the ones they replaced were perfect. My A/C uses a very unique size and Atomic (fortunately) has them. I buy them from Atomic rather than pay 3 or 4 times as much to get them from my A/C service. Totally satisfied.