This is the OEM part that is the wall fitting that holds the skimmer in the upright position. It connects to the small grey/black hose that attaches to the skimmer approximately halfway up the skimmer. The orientation of the gaskets are very important when installing. The male portion goes through the wall from the outside. Be sure and put one rubber gasket on before you insert it through the wall. On the inside of the pool, place one rubber gasket against the wall with the paper gasket put on last. The paper gasket should be underneath the cap as you screw it on. The paper gasket allows the nut to spin on and not pinch the rubber gasket.