Instructions for installation were lacking in clarity.  It tells you to remove the incinerator splash guard, but if you remove whole rubber splash guard, the disposal will not connect up.  You have to remove just enough of the thin rubber part from the rubber gasket that holds disposal.  I did not remove enough the first time and flange would not fit in.  I then trimmed any of the thin rubber that extended beyond the edge of the metal disposal flange that fits into the sink drain.  After doing that the Silgranit flange snapped into place.