This is the required piece of hardware to attach the oil return line to the oil pan, valve cover, or other convenient place. It is tapered with large wcrew threads that bite into the punched hole made in the oil pan. The hole must be punched, not drilled to ensure proper grip.
The head of the bolt is threaded to accept the hose fitting from the oil return line from the Frantz Oil Filter. There are many other optional uses for this bolt.