#66X Expanded Flange Casing Bead is used as a stucco/plaster stop to provide a screed edge and protective finish trim while terminating plaster or thin stone in a clear straight line at doors, windows, or other openings. Also, recommended as an edge divider between plaster and other dissimilar materials. Not recommended at base of wall in lieu of a FHA-7 Foundation Weep Screed.