Heavy Duty Bronze "Post" Mail Slot Includes Slot and interior Plate 13" x 3 1/2". Exterior Closure Spring loaded to keep the elements out. Comes with hardware to install. Different length screws for different thicknesses of doors.13" slot external dimensions:13" W x 3-3/4" H. Opening dimensions: 11-1/4" W x 2-3/8" H (± 1/2"). Mounting bolts are on 12" centers. Please refer to the photos and ask any questions that you may have. This is a Heavy Duty Slot weighs 4 Lbs