Filter having mutually interacted filter housing and filter cartridge

A filter having a filter housing and a filter cartridge, said filter housing having a closed end and an open end, and said filter cartridge having a first end and a second end, said filter housing and said filter cartridge being coupled with one another from outside and inside respectively, characterized in that:

• at least an oppositely extended wall is mounted on the inside of said closed end of said filter housing;
• at least a flat step is formed on the outside of said first end of said filter cartridge;
• and
• a stopper is formed adjacent to said flat step, wherein a gap having, a width larger than a thickness of said oppositely extended wall is defined between said stopper and said flat step, said oppositely extended wall of said filter housing is such located to axially correspond to said flat step of said filter cartridge that a rotation causes said oppositely extended wall to be screwed into said gap so said filter housing and said filter cartridge are pulled out together by obstruction caused by said stopper when said filter housing is loosened from a base by another rotation.