I'm sorry I didn't read the reviews first because when I tried to install it (I have a lot of filters in this system changed), it just didn't fit. When I measured all four I found they were 4.5" deep. Other sizes are fine. It would be a mistake to advertise them as 4" deep. Now I have three perfectly packaged filters that don't fit and one that's slightly torn and they're too clumsy to send back.
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