Specifically designed for use in cast-iron fittings where the threads have been damaged, the Test-Tite Flush Mechanical Cleanout Repair Plug restores functionality to cast-iron cleanout tees. This cleanout plug features an innovative design that creates a seal with the smooth surface behind the damaged threads to provide an airtight seal. Compatible with all brands of cast-iron fittings, this repair plug sits completely flush inside and out of the tee and cannot fall into the pipe.