Anderson Manufacturing O45 1.5-Inch Standard Open Stem Plug is part of the Standard Open Plugs of Anderson Manufacturing Company. Open stem plugs use the same straight-sided rubber, large wing-nuts, and corrosion free materials as closed plugs except they have an opening that passes through the center of the stem. This opening allows the introduction of air or water pressure into the system you are testing. National pipe threaded tops on both sides of the open stem plugs make this versatile tool easy to set up for pressure testing, clearing blocked lines, or blowing out lines for winterization. The plug top is a combination 1/8-inch pipe thread and 3/8-inch hose barb. This specific product with part number O45 has a rubber diameter of 38 millimeters or 1-1/2 inches. This is used for a 1-1/2-inch pipe application. The Pressure Induction System of Anderson allows you to induce and measure water or air pressure in plumbing lines. The Pressure Tester used in conjunction with Open-Stemmed Plugs allows you to access plumbing at the pump, returns, skimmer or equipment without cutting lines or depending on leaky threads. It is as simple as choosing the appropriate plug for the line you are testing and quick-connect it to the Pressure Tester.