A cleanout plug is a pipe fitting that is normally used to allow access to a sewer system. It is mainly used on a combustion spudgun. There are two parts: a cleanout adapter, and the plug itself. The cleanout adapter is just a female adapter, and the plug is just a plain NPT plug. Because these fittings are used for sewer lines, there are no pressure rated cleanouts. This fitting comes in both PVC and [ABS pipe|ABS]. Copper and cast iron cleanouts exist, but are expensive and not used on spudguns.