Instruct: Classify an Amazon review into positive or negative sentiment.
Query: Stay away from these

I purchased a couple of these about two years ago. They really are unsatisfactory. As mentioned in a previous review these items are simply not flat. Because of their crown they are very difficult to work with so they sit in the drawer. I did find, however, inserts that fit my Rigid table saw. Got them from LeeCraft. Now these are excellent plus I installed a splitter behind the blade.