Architectural Mailboxes 7540B-10 Mailbox Adapter Plate, 4" x 4", Black Can be used to attach Architectural Mailboxes post mount Mailbox to a wooden 4x4 post Multiple bolt hole patterns, including 4x10 bolt hole pattern and 11-1/4&Prime; side flange mount screw pattern Can be installed onto a wooden post as a top mount, side rail mount and front cantilever mount to suit your needs Durable galvanized steel construction Includes mailbox mounting hardware and spacers used for T2 sized mailbox installation Finished with durable black powder coat Supports up to a 50 lbs. mailbox