Create/modify materials - Reflection

Merry christmas everyone!

As a fun task I am working on a script that converts V-ray materials to corresponding Rhino materials. I am able to extract data from my V-ray materials, but I have a problem creating the new Rhino materials. Using the create/modify material, I only get an input to modify the Gloss amount of the material, and not the reflectivity. I have tried looking around for other components, but with no luck.

Anyone who has an idea on how to write the reflection value of a material?

Thanks in advance!