Product review (2 stars): Drainage is MUCH better and the disposal is still quiet
The disposer is powerful and quiet, but the drainage problem with this collar was totally unacceptable.

Per the suggestion below about enlarging the vent holes, I cut V's from the two holes toward the center (to the line on the underside of the rubber). That helped, but not enough, so I cut slits about 2/3 of the way up on each of the four down-sloping sections. Then I used a regular hand-held paper punch to make a hole at the top of each slit. Drainage is MUCH better and the disposal is still quiet.