Cherne mechanical test plugs can be used in a wide variety of applications including DWV and stack testing. With a variety of end-of-pipe and in-pipe options available, it's easy to find the right mechanical test plug for the job. This clean out gripper plub is made with glass-reinforced ABS plastic and a natural rubber cleanout plug that is guaranteed to seal damaged threads. The black color blends in well with cast-iron pipe, featuring stainless steel hardware that prevents corrosion. Cherne Industries is a global leader in pipe plug, blocking and testing.