Decorative Grille, Vent Cover, or Return Register. Made of Urethane Resin to fit over a 4"x16" duct or opening. Total size of vent is 6&rdquo;x18"x3/8", for wall and ceiling grilles (not for floor use). Historic Reproduction from a unique grille made in New York in the 1870's to 1900's Easily replaces old louvered type grilles Fine 3-Dimensional Detail Hand Rubbed Bronze Finish Made from a high quality urethane resin, dimensionaly stable, won't rot, rust, corrode or grow mold