Mailbox support kits for #1 and #1A mailboxes (not included).
Single (MBB-S): Packaged with all parts and hardware to mount one #1 or #1a standard rural mailbox on a Model 20-ST support.
Double (MBB-D): Packaged with all parts and hardware to mount two #1 or #1A standard rural mailboxes on a Model 20-ST.
Multiple (MBB-M): Individually packaged with all parts and hardware to mount one #1 or #1A standard rural mailbox on a Model 20-MT support. The Model 20-MT will accommodate five #1 or four #1A mailboxes.