Naiture 10" Solid Cast Brass Heavy Duty"Post" Mail Slot Antique Brass Finish Made of heavy-duty solid cast brass which will never get rust. External dimensions:10" W x 3-1/8" H. Opening dimensions: 8" W x 1-7/8" H ( 1/2"). Mounting bolts are on 9" centers. Finish: Antique Brass Spring-loaded closure keeps out elements. Includes fastening hardware. With a decorative border and a front design that reads POST, this heavy duty mail slot is a regal addition to any home.