Fort Knox Mailbox Fortress B Fortress - Black Fort Knox Fortress - Black - Mailbox Only - Maibox size: 12"x12"x23" 98 LBS. of Steel! (Mailbox only) 1/4" Thick steel shell & 3/16" reinforced steel doors Incoming mail slot: 1 3/4" x 11 1/2" & Outgoing compartment 3" x 11 1/2" NOTE: Not hardware included