Abstract: There is disclosed apparatus for closing a threaded opening in a container. A flexible plug capable of fitting within the threaded opening having a top and a bottom is provided. A flexible gasket larger than the opening is located at the top of the plug and a first rigid disk capable of fitting within the threaded opening is located at the bottom of the plug. A second rigid disk larger than the opening contacts the gasket. Means passing through the gasket and plug for causing the two disks to move toward each other compress the plug so that is firmly contacts the threads of the opening while the gasket is pressed against the opening by the second rigid disk. An excellent seal is thereby attained.

Abstract: A filter for liquids contained in a tank having an existing top opening. The inventive apparatus attaches to the top opening. A weight hangs from the attachment means by a cable. A filter floats on the liquid's surface and slides along the cable. The apparatus is adapted for use in two-pipe systems.