Showing Thickness for a Surface

I thought I had seen in a Rhino 6 feature video that it was possible to change the display settings to show thickness for surfaces.

I have searched through the display settings and the manuals and cannot find anything to this effect.

If I can display a surface with thickness, what setting would it be?

The first item from google after searching “Rhino 6 display surface thickness”


Thanks, you get different search results than I do.

I had been looking in all the wrong place. Object property rather than display property.