RMB20R00 Mounting brackets for round steel mailbox posts. Fits standard size mailboxes. These heavy-duty mailbox mounting brackets are constructed from galvanized steel. Includes mailbox mounting hardware and instructions. Features: -Mounting bracket. -Includes mailbox mounting hardware and instructions. -Fits standard size mailboxes. -Constructed from galvanized steel. -For round steel mailbox posts. -Carded. -Dimensions: 1 - 5.5" H x 5.5 - 10.63" W x 1 - 10.63" D.