Abstract: A clean out plug for removably plugging a clean out opening in a fluid line has an externally threaded body with an upper surface having an opening into a cavity in the body which houses a reversable key which is removeable from said body, and which has a smooth surface on one side and a tool engaging projection on the reverse side. In a first position in the cavity, the key presents a smooth flush surface with said plug body, with said projection projecting down into said cavity. In its reverse second position said key presents said tool engageable projection projects above said upper surface of said clean out plug body, such that a tool can be used to engage said projection and remove the clean out plug from the opening it plugs.