Heavy-duty 100% cast aluminum in a lightweight construction. Rust-proof. The Pony Express image adds historic authenticity to this style that also features security locking on the front door and a solid brass mail flap with an opening of up to 2". Each mailbox comes with 4 keys. Mounting hardware is not included. Mail flap dimensions are 10 7/8" x 2 1/2".Assembled size is 16 1/2" l x 11 3/8" w x 44" h.