4C Standard Mailboxes are constructed of heavy gauge aluminum with stainless steel components for maximum durability both indoors and out with a shelter. Corrosion resistant, weatherproof powder coat finish protects the units from the elements, while the riveted shelves and concealed hinges limit pry points for extra security. Carrier access door provides easy access for Postal Letter Carriers to release the master loading doors. Tenant doors meet the new compartment minimum size requirement of 3"H x 12"W x 15"D. Most units meet the USPS requirement for 1:10 parcel locker to tenant compartment ratio, and all units meet the USPS 4C requirements which comply with ADA standards.