They are in fact a two way speaker, though the fret has a third circle (for a midrange I think) but there is nothing behind it.
The fret comes off easily, just pull the top corner out and slide your finger round to disengage the six pops.
I have S30s in my dining room, and they are a fine speaker. $65 seems reasonable to me. I don't think they suffer from foamrot, mine haven't anyway.
Andy T.