OATEY 42742 2-1/2 in. Brass Cleanout Plug

The 42742 is the 2-1/2 inch brass cleanout plug. The plug is countersunk and tapped, so it threads into a 2-1/2 inch cleanout ferrule or tapped cleanout body. If your cleanout is a different size, Oatey makes the same countersunk and tapped plug in 1-1/2, 2, 3, 3-1/2 and 4 inch.

Countersunk means the drive recess is sunk into the face of the plug rather than raised, so the plug sits flush or nearly flush in the ferrule instead of standing proud. You drive it with a cleanout plug wrench or square socket that drops into the recess, not with a pipe wrench on an outside boss. That flush profile is what lets the plug sit under a finished floor or close to a wall where a raised-head plug would not clear.

Yes, as long as the ferrule threads are 2-1/2 inch and still sound. The 42742 is a tapped brass plug sized for a 2-1/2 inch cleanout, and brass in a cast iron ferrule is the usual repair when a plastic plug has split or cracked out. Clean the female threads before you set it; if the ferrule threads are damaged, the ferrule itself has to come out.

It is the plug alone, a single brass piece, model 42742. Nothing else is in the box. Brass cleanout plugs are sealed with thread sealant or pipe dope on the male threads; plan on supplying that, and avoid overtightening into a cast iron ferrule.

The 42742 is listed at 0.32 (product weight) with a volume of 0.003, so it is a small, dense item that stocks easily on a van or in a bin. Buyers standardizing a building usually carry the 2-1/2 inch alongside the 2, 3 and 4 inch plugs, since those are the sizes a cast iron DWV stack and branch cleanouts actually use.