California C-35 Contractor Exam Practice 2026 – Complete Prep Guide

FRB refers to a type of metal plaster base described as Flat Rib Lath with Backing. Here, the F stands for Flat, the R for Rib, and the B for Backing, and it specifies that the item is lath (a perforated or ribbed metal sheet used as a backing for plaster) with backing material behind the ribs. This combination provides a keying surface for plaster while the backing adds rigidity. Other options don’t fit the abbreviation because they either mention base instead of lath or omit the backing or ribbed-flat geometry that FRB conveys.