Oatey 42745 Brass Cleanout Plug, 4-Inch 1 1/2"" countersunk and tapped. 2"" countersunk and tapped. 2 1/2"" countersunk and tapped. 3"" countersunk and tapped. 3 1/2"" countersunk and tapped. 4"" countersunk and tapped. 1-1/2-Inch countersunk and tapped 2-Inch countersunk and tapped 2 1/2-Inch countersunk and tapped 3-Inch countersunk and tapped 3 1/2-Inch countersunk and tapped