Abstract: The specification discloses a two-piece twist apart filter housing adapted to be interposed in a conduit supplying or receiving air or other medium from a device, wherein the two parts of the housing can be twisted apart to permit replacement of the various types of filter media without detaching either end of the filter housing from said conduit. There are also disclosed particular filter assemblies utilizing said filter housing wherein there is provided a particulate filter, a coalescing filter, and an odor filter assembly which can easily be removed and replaced when needed without removing the filter housing from the supply line.