Key keeper unit- with button-aluminum with built-in spst momentary low-voltage pushbutton (Nat. Anodized Alum. Finish). The Bommer® 5620-628PB flush mount key keepers is designed specifically to mount in conjunction with aluminum lobby panels, directories, and mail boxes. The 5620-628PB key keepers is U.S. Postal Approved, and are required when mailboxes are installed behind a locked entry door. This allows the Postman access to the mail boxes, without having to bother (or wait for) any of the building's tenants. These key keepers can be mounted vertically or horizontally and include the mounting bracket and screws for the installation of the postal lock (supplied by the local post office).