OATEY 42743 3 in. Brass Cleanout Plug

The 42743 is a 3 inch brass cleanout plug, countersunk and tapped, so it threads into a 3 inch tapped cleanout opening such as a cast iron ferrule or cleanout tee with 3 inch threads. Size here refers to the thread size of the opening, not the pipe run, so measure the tapped hole rather than the pipe before ordering.

Countersunk means the plug has a recessed square or hex socket in its face rather than a raised nut, so once tightened it sits down in the opening instead of standing proud. That is what you want where a cleanout lands in a finished floor or a tight chase and a raised head would foul the cover plate. The 42743 is a 3 inch countersunk, tapped plug.

Oatey makes this countersunk, tapped brass plug in 1-1/2, 2, 2-1/2, 3, 3-1/2 and 4 inch. Model 42743 is the 3 inch. If you are standardizing cleanout plugs across a building, those six sizes cover the usual drain and waste openings.

Brass is the usual choice where the plug has to come back out years later. Plastic plugs can seize or distort in a metal ferrule, while brass threads against cast iron or brass hubs and backs out with a wrench when the line needs rodding. The Oatey 42743 is solid brass in the 3 inch size.

It is listed at 0.398 in product weight, which is the kind of small, dense item that adds up fast if you are stocking a truck or building a cleanout kit for several risers.