all i do is pack a tight ass joint or blunt and leave about a half or 3/4 inch at the end and roll up a little paper real tight and let it go in there, it doesnt actually filter the smoke, but it keeps the weed out of your mouth and lets you smoke it without burning your mouth. also, it makes the jay easier to hold if b/c you can hold it back there instead of messing up the perfect jay by crushing the weed. just my opinion.