Product review (5 stars): OMG!  It WORKS!
Wow, I can't believe it....it WORKED!  I had (horrible) visions of removing my disposal and the plumbing connected to it and trying to replace the shield that way.  Another Saturday shot.  Instead I read about this replacement that is simply pushed down into disposal sink inlet and decided that for the modest price, it was worth a try.  I was astounded that it fit the inlet perfectly!  And not only that, but as others have said here, it made the disposal almost (not quite, but almost) silent!  I have no idea how this little thing did that, but it did, I promise you.  As long as you have the right size for the right disposal, you are not going to believe how simple and effective this shield is.  Wow.