The 6-1/2” extension between the rubber and the wingnut on these plugs allows a seal to be made farther inside a pipe. They are commonly used for skimmers, cleaner lines, and therapy heads, or can be used to bypass a leaking section of plumbing near the wall of the pool to test the remainder of the line. The plugs are made with durable brass hardware, solid rubber, and a corrosion-free wingnut. Our heavy-duty plastic wingnuts are about the same strength as brass wingnuts (except in particularly dry environments), but are lighter and will not corrode over time. Anderson Plugs are built with durability in mind and will remain easy to tighten and leak-free even after years of use. Straight sided rubber is the best choice for accurate, safe pressure testing in swimming pool plumbing lines, but it’s important to choose the correct sized plug. Choose a plug size that is about 1/8” smaller than the inside diameter of the pipe opening you are plugging off. The measurement listed for each size is the actual diameter of the unexpanded rubber.