You can define variations of an objects with a different number polygons. The renderer chooses the object depending on the size on the screen. The objects can even have different materials (Level of Detail Shading)
Benefit
Optimize rendering performance
Finetune visuals: very high polygon objects might produce rendering artifacts if displayed very small on the screen
January 2010 - Click-VR Visualizer 1.11 now available! October 2009 - Click-VR Visualizer 1.1 now available! Support for 3ds Max 2010 + support for 2D flash overlays + global illumination + Dynamic Depth-Of-Field + real time area shadows + vray lightmaps/materials + more