Yeah one of my first purchases after I saw what the inside of a stock intake looked like!!! The "filter" is like a chunk of steel wool but with thicker grade wool.. kinda like metal shavings size... All it does is provided a turbulence effect and allow surface area for oil to collect on and then drip into the cup. I have removed mine and blown brake cleaner thru the entire line and cleaned out the cup. But it's really not needed