Salsbury Industries 4870BLK Deluxe 1 Sided in Ground Mounted Mailbox Post, Black 2-sided deluxe mailbox posts for two mailboxes include two 14" W x 3-1/2" D x 3-1/2" H arms 2-sided deluxe mailbox posts for three mailboxes include one 14" W x 3-1/2" D x 3-1/2" H arm and one 24-1/2" W x 3-1/2" D x 3-1/2" H arm 2-sided deluxe mailbox posts for four mailboxes include two 24-1/2" W x 3-1/2" D x 3-1/2" H arms Includes: Sided Arm