I’m doing a remodel and the plumbing inspector dinged me on a few things–one being he wants a “mission clamp” connecting the new 2″ ABS to the old cast iron in our root cellar that goes out the foundation wall and connects to our clay sewer line. Currently, I have this configured using a neoprene doughnut wedged into the cast iron. How can I fit a “mission clamp” onto this cast iron hub that is bigger than the ABS pipe? What exactly is a mission clamp? Help!!!