A filter cartridge includes a key ring with at least first and second protrusions to engage a lock-out assembly in a filter head, permitting the cartridge to connect to the filter head. A filter system includes a filter assembly, including a filter cartridge and a cartridge housing, connected to a filter head, in which the filter head includes an adapter assembly with a lock-out mechanism. The lock-out mechanism is unlocked by a key ring on the filter cartridge. A method of installing a filter assembly includes using protrusions on a key ring on a filter cartridge to unlock an adapter assembly in a filter head to allow for connection between the filter assembly and the filter head.