Product review (5 stars): Cut the old one out and insert this one. No need to remove the disposal.
Use this when your old one gets old and slimy and doesn't close like it used to. The advantage to this one is you don't have to remove the disposal. Just cut the old one out from the top leaving its outside ring in place then insert this new unit and push it down until the ridge at the bottom goes into a groove in the disposal. You have to fiddle a little to get the ring into the groove all the way around but it's not hard. The next time this one needs to be replaced just yank it out and put the new one in. Easy peasy.