Material: Corrosion-resistant steel. (Model 4360 is standard).2. Designed to match supply air models 4320, 4320CB, 4320F and 4320M in appearance and construction detail, except that the air pattern controllers are not required and are omitted. This version is for ducted return applications; for connection to flexible or rigid round duct or square duct.3. Removable face has concealed latches for easy access to optional damper.4. Perforated face has 3/16" (5) diameter holes on 1/4" (6) staggered centres.5. Standard finish is AW Appliance White.