PRODUCT DESCRIPTION The In Ground Steel Mounting Post is made of heavy-duty 10- and 14-gauge galvanized steel with a durable powder-coated finish. Use this 43" in-ground post to mount any Mail Boss locking mailbox. The post will fit over a 4"x4" wood post for deep installations and reinforcement with rebar. FROM THE MANUFACTURER The In Ground Steel Mounting Post is made of heavy-duty 10- and 14-gauge galvanized steel with a durable powder-coated finish. Use this 43" in-ground post to mount any Mail Boss locking mailbox. The post will fit over a 4"x4" wood post for deep installations and reinforcement with rebar.