Product review (2 stars): Almost good.
It fits just fine and it does what the baffle should do except for one thing.  The stopper (original equipment) will not seal against this so you cannot fill the sink to use it for washing dishes, or in my case, we use the small side of the sink to defrost frozen meats by filling the sink and putting the sealed freezer bag into the water.  I bought two of these and thought one might be defective, but neither one works. I still have the original equipment baffle and it still seals just fine.  It has a lip that extends upward and forms the seal with the stopper.  I bought these so that I could take one out for heavy duty cleaning (they get very greasy on the bottom over time) but still have one in place. It is an inconvenience.  I didn't realize this shortcoming until after the 30 day return window had passed.