Lets you use a regular 3ds Max material as a mental ray shader. Depending on the component to which this shader is assigned (Surface, Shadow, Displacement, Volume, and so on), the mental ray renderer uses the appropriate material component.
For example, if you want a mental ray material's Surface component to look like a standard material you have, assign Material To Shader as the Surface shader, and then assign it the standard material.
Chain-link Standard material assigned to a mental ray material by using Material To Shader
If you need to further adjust the material, you can repeat these steps (without having to reassign the Material To Shader).
Click to display the Material/Map Browser and choose the material to use for shading.