Are you talking about the round little screens to go into the bottom of a bowl? If so they are not used for proper pipe smoking, as they would have to be removed and run the cake build up we work hard to get to. They are used for the Wacky Stuff for whatever reasons. If you did use them they could get clogged up over time. Removing them could prove difficult, as you would have to dig them out possibly damaging your bowl.