PRODUCT DESCRIPTION The In Ground Steel Mounting Post by Mail Boss is made of heavy-duty galvanized 10- and 14-gauge galvanized steel with a durable powder-coated finish. Use this 43? in-ground post to mount any curbside Mail Boss locking mailbox. The In Ground Post should be buried approximately 12? in ground in order for the incoming mail slot of the Mail Boss mailboxes to be within USPS specifications of 41?-45? above the road side surface. This post will fit securely over a treated wooden 4?x4? post for deep installations and reinforcement with rebar stakes. 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.