The 550 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 50 tenant doors measuring 6-3/8"W x 3"H Each tenant door features a 5-pin cam lock that comes with two keys and a clear plastic window number slot for easy identification. The units are open in the back and designed to be loaded from the rear. Silver Color