Mobil 1 now uses Mann+Hummel as their supplier. M+H bought out Bosch's ownership stake ad now have comolete control. More specifically their Purolator brand. M+H produces Wix, Purolator, Carquest, and Napa among others. Older M1 oil filters without the A were the Champion Labs made filters. Champ Labs filters were 99% @ 20 microns for 15K; M+H filters with the A are 99% @ 30 microns. M1's website still list a synthetic blend media which was also used in the Champ Lab made M1s.