The 450 Series Horizontal Mailboxes are developed for use in private institutions that are not serviced by the USPS, such as military bases, colleges, universities, and hotels. These custom, heavy-gauge aluminum mailboxes meet all USPS regulations except those pertaining to compartment size. The smaller compartments allow for more mailboxes per module, and are useful in areas with limited wall space. Features 59 tenant doors measuring 6-3/8"W x 3"H, and 1 Master Load door. Each tenant door features a 5-pin cam lock that comes with two keys and a clear plastic window number slot for easy identification. Please note that one mailbox unit door will be used as a master door and cannot be used as a tenant door; it can, however, be used as an outgoing mail slot or office dropbox, upon request. Silver Color