Need info on Acousti-Phase Bookshelf speaker, midranges ??


I'm not much of an AudioFile.
I've had these Acousti-Phase Bookshelf speakers for ..........EVER!
I just noticed that the lower speakers on both speakers have had there foam just crumble.
I'de, for some reason to replace them. I did take one out in the hopes it would tell me something.... it didn't. I don't know the range OR how many OHMS.
All I know is size. They are about 6 1/2 Diameter and 2 1/2 " deep, They have 4 screws hold them in.

ANY idea whatI can replace them with ?
What's the correct impeadence, range ?

Many thanks, AudioTedII