4C standard horizontal 3700 series mailboxes are U.S.P.S. approved and meet the specifications of USPS-STD-4C . Ideal for apartments, residential communities, commercial buildings and many other applications . Includes a 10.75 in. W x 0.75 in. H mail slot and weather protection hood. A compartment equivalent to two 3.25 in. high standard doors is used for outgoing mail collection . The compartment is labeled Outgoing Mail . The outgoing mail compartment includes the U.S.P.S master lock access door and cannot be used for mail distribution . Fully integrated or stand-alone parcel lockers offer tenants a convenient way to receive packages on site . Factory installed 0.75 in. W x 0.25 in. D trim and a solid rear cover . Comes standard with lock and keys for each individual mailbox . Does not include master lock for U.S.P.S. entry; must be provided by U.S.P.S.. Made of heavy gauge Aluminum and Stainless Steel hardware . 16.375 in. W x 17 in. D x 48 in. H (75 lbs.)