But my question is: is there any difference in the outward appearence of the cannister itself--other than color that would let you know whether it was an AC or a Fram. Thanks. Jim Carter's catalog has a note which says "Note, Fram uses corrugated cone bottom". I ask the "sales person" what that meant and she said something to the effect that Fram cannisters were dippled or corrugated on the bottom and AC's were not. Anyone confirm this or shed any other light on the subject?