Thanks for the reply. I think I understand it - the mass ring is placed in the neck of the diaphram, so that LF gets deeper and HF isn't sacrified. Is this it?

Is these rings placed inside the neck, or could I say its like being placed in the voice coil former? If so, then its not a part of the basket, and that would mean the 2225 and 2235 baskets are exactly the same, because the mass ring is placed on the diaphram. So if I buy a 2235 recone kit, it should have these mass loading rings? Or at least have the mass increased in a simlar way?

Thanks!
Adrian