CP plug, also known as a Compression Plug, is a type of plumbing fitting used to seal off the end of a pipe or tube. It consists of a threaded plug with a compression nut and a rubber or plastic washer inside. When the plug is threaded into the end of the pipe, the compression nut is tightened, causing the washer to create a watertight seal. CP plugs are commonly used in various plumbing applications, such as sink drains, bathtub drains, and other fixtures where a temporary or removable seal is needed. They are easy to install and provide a reliable method for closing off pipes securely.