The Pondmaster / Danner  Supreme Venturi Assembly kit attaches to the front end of the Supreme magnetic pump Drive 9.5 - 18 or the Pondmaster Pond Mag 9.5 - 18 pumps. The Venturi Assembly is used in conjunction with the Pondmaster Fractionating Impeller Assembly (sold separately) for protein skimming with an appropriate protein skimmer and for aeration.