You need to have a mesh that has Subdivision surface modifier on. Every button should have enough info to use the tool. Shape Freeze - Enables to change topology of Subdivision surface model while keeping the resulting shape as same as possible.Higher interation numbers yield precise results. has settings for number of subdivisions, number of iterations of the algorithm. Unsubdivide - takes a mesh that resulted from a subdivision modifier being applied (In blender or in any other application) and recreates the original low-resolution mesh.Single step operator that can be called with a shortcut with arbitrary number of iterations.

Neighbours levels, Number of iteration settings Live, or 'Simulation' mode of this tool, which works realtime during modeling Inverse subdivision snapping: snaps mesh vertices in edit mode so that if the subdivision modifier is used, the resulting surface is as close as possible to the surface.