Intex Large Pool Strainer Assembly w/Blue Strainer Cover Large Pool Fitting w/ Blue Strainer Cover for Intex Brand 18' or Larger Pool System Not Integrated Strainer, great for connecting Vacuum Kits and without possible blockage by debris. Set come with one of each: Pool Fitting w/ thru opening, Blue Strainer Cover, Rubber Gasket and Screw-on Nut Hose Connections side with thread size measures roughly 2-1/8"~2-1/4", designed for connecting Intex plunger valve or pool hose Strainer side with thread size measures roughly 3"~3-1/8, designed to connect Intex Type B Convertor/Adapter for Skimmer of Vacuum Hose Connection