Editing Main Render Settings (section)

=== Smoothness ===
''Smoothness currently only affects the skin. The fur has simplified lighting, and does not currently support it.''

Smoothness determines how sharp or diffuse light reflections are. There are 2 possible sources for the Smoothness strength: the albedo texture alpha channel, or the metallic texture alpha channel. If the metallic texture alpha texture is selected, but no metallic texture is provided, then the Smoothness will be directly settable with a slider instead