**Use this Schedule 40 PVC MPT x Slip Adapter to transition from PVC pipe to a male pipe thread (MPT) connection. The PVC slip connection requires primer/glue. Selecting the correct size fittings to match your PVC pipe can be confusing if you do not already know what size PVC pipe you have. All plumbing grade PVC should have size and rating information imprinted on the outside of the pipe. PVC pipe is named for the inside diameter, commonly referred to as "a nominal size". If not able to locate this information then simply measuring the inside or outside diameter will help you determine the correct pipe size using the chart below. **PVC Pipe Size Table** Nominal PVC Pipe Size **1/2"** **3/4"** **1"** **1 1/4"** **1 1/2"** **2"** Average Inside Diameter 0.622" 0.824" 1.049" 1.380" 1.610" 2.047" Actual Outside Diameter 0.840" 1.050" 1.345" 1.660" 1.900" 2.375" Once you determine your PVC pipe size then fitting selection is easy - just match the nominal pipe size to the corresponding fitting size. Example: If your pipe measures 0.824" ID (inside diameter) which is 3/4" PVC pipe, you will select 3/4" PVC fitting.