4C Commercial Mailbox, Wall Mt. USPS Approved, Total Parcel Lockers 2Florence 4C mailboxes are USPS Approved and meet or exceed STD 4C requirements for new construction and major renovations. They are also ideal for private delivery applications. With numerous pre configured 4C modules available, be sure to refer to USPS Approval guidance in product details below when selecting pre configured 4C mailboxes for your project FINISH OR MATERIAL Heavy gauge aluminum construction LOADING & MOUNTING Front loading 4C mailbox