Seals air tight! (Does not rely on threads to seal.)
Back pressure actually increases sealing ability!
Completely flush inside and out!
Home Improvement Rough Plumbing - IPS Corporation Drain Cleaning Equipment : 2 Inch FLUSH MECHANICAL CLEANOUT REPAIR PLUG.Stainless Steel flast head screw!. Cannot fall into the pipe!. Comes with wrench!. Patent 7,464,727. UPC: 012181836873.