Made entirely of aluminum, Salsbury 3500 series USPS approved 4B plus vertical mailboxes feature a durable powder coated finish available in five (5) contemporary colors aluminum, brass, bronze, sandstone or green. Surface mounted units mount directly to a wall or other flat surface and are secured with mounting hardware through the back panel. Vertical mailboxes are approved for US Postal Service (USPS) mail delivery. Units feature 5-1/2 in. W x 16-1/4 in. H extruded aluminum doors. Each door includes a five (5) pin cylinder cam lock with two (2) keys and a 2-1/2 in. W x 5/8 in. H indentation to accommodate a label (included) identifying the tenant's name and/or box number. Mailboxes are available in units with three (3) to seven (7) compartments. Each compartment is 16-1/4 in. H x 5-1/2 in. x 6-3/4 in. D.