Another scenario could be that you have created a negative area in your model for example when sculpting or combining a component with a deep subtracted model, this tool will easily remove anything below a given height. For example if you've imported an STL model that has a lot of thickness, which can be quite typical of 3D scanned data, this tool will allow us to simply trim away the unwanted thickness. This tool allows you to trim or flatten the bottom of a component(s).
We have added a new model editing tool which replaces the “replace below” gadget.