When you take the filter off, there is a huge nut and a type of sleeve ( sort of a tread extender for the filter )that holds and connects to the cover. I can't remember what size the nut is, maybe 1"1/8th". Anywho, remove the nut and the adapter housing slides off. And if you are intending to leave it off and run without it, the filter will screw right on with no problem.HTH
Donnie