Lightening a clearance area

I have having a hard time changing the looks of a clearance area for a VAV Box.
The attached VAV Box Family is Downloaded from Johnson Cintrols / Envirtotech.

I am trying to lighten the clearance and give it a "Smaller LT scale"

Any help Would be appreciated.

Thanks,
Andre

When editing the family; create a new parameter called clearance. create a new material that has the color and transparency setting you desire. edit the parameter you created earlier; apply the material with the transparency to be used by the parameter. Next, select the objects that will need this transparency setting and apply this parameter to them in the properties. I may be missing a couple of steps; but this is the concept to use for this application.