Security Chute Only The Security Chute is a secure, "" shaped steel insert that can be used in a pilaster (column mount) setting of your own design. Designed to secure to the back of the decorative Manchester Door, this chute transforms a standard mailbox into a locking version. Delivered incoming mail automatically drops out of reach, where it is safely stored until retrieval from a locked rear access door. Outgoing mail can be kept in the designated slot below the incoming drop. Features Constructed of steel. Powder coated in black for durability. Dimension 8-0.5 W x 20 D x 36 H in.