champion laboratories filter question?

[kcfx4]

as i understand this is what you guys call ecores? The filters i will be refering to fit kawasaki ope engines filter # 49065-2078, wich is a jd am107423 (champ made), ace ph2840 (champ), super tech st4967 (champ), stp s4967 (champ). on the base plate of ech of these champ made filters have an "AA" engraved in it, the jd simply says AA, the ace says AA2, the st and stp say AA1, so what does the AA, AA1, AA2 reference?
on a side note my m1 that fits my truck not mower says ZZ

 

[Sayjac]

ST/STP 4967 is a small, Can't speak to others mentioned or the meaning of AA on base plate.

Easy to tell though, look down centertube/outlet hole. See a black cage like design with rectangular openings, ecore.

 

[kcfx4]

sayjac, all the numbers referenced are direct interchanges for the kawasaki 49065-2078, didnt note a black cage on any of them

 

[Sayjac]

No black cage centertube inside, not ecore. For some reason the small (<3" dia.) Champs have stayed with a classic design.