hawk. i think he's referring to the mold or lip/plate of those discs.. the valkyrie,firebird,and Viking I know are part of the same family of drivers.. They are all 9 speed rated and have the same lip i've been told.
That's probably what he's referring too..
Kindof like the beast,orc,starfire are all 10 speed rated and all have huge rims.

-Scott LEwis