A zero clearance insert (ZCI) is a one of the most beneficial accessories you can use with a table saw. It’s a replacement for the throat plate that comes with your table saw. The purpose of a zero clearance insert is to bring the distance between the saw blade and the nearest supporting surface down to zero. As in zero clearance. In other words, there is no gap between the table saw top and the saw blade. The insert is as close as it can to the saw blade without physically touching it.