Designed for use to seal piping or to hold pressure while testing your piping system. The Oatey Plastic Mechanical Test Plug mechanically seals inside the designated pipe. It is excellent for plugging open-ended pipes. The plastic body has minimal to no rusting or corroding for a long-lasting use. The plug's wing nut helps make tightening and removing the plug easy. Size: 3 In. Flange Material: Zinc Gasket Material: Rubber WARNING: Cancer and Reproductive Harm -www.P65Warnings.ca.gov. -