US Patent 7135113 Keyed filter assembly

A filter assembly is disclosed including a cartridge member having a body portion and a cylindrical neck portion depending from the body portion, the neck portion having at least one lug depending radially outwardly therefrom having a keyed surface formation thereon, and a reception member defining an axial bore for receiving the neck portion of the cartridge member, the bore having at least one reception area provided therein for receiving the at least one lug, the reception area having a compatible mating surface formation defined therein for engaging the keyed surface formation on the lug so as to prevent engagement with an incompatible cartridge member.