had multiple compartments for the centralized delivery of mail to the residents of a building or an entire neighborhood, instead of door-to-door or curbside delivery. Cluster Box Unit New cluster box unit (CBU) specifications were then developed in 2005 and became the standard for ALL manufacturers. The USPS began to officially license this new standard in 2007 – now manufacturers must be approved and licensed in order to manufacture the CBU. Like its predecessor the NDCBU, each CBU has multiple compartments for the centralized delivery of mail to the residents of an entire neighborhood, eliminating the need for door-to-door or curbside delivery. This new design also incorporates a parcel locker and an outgoing mail slot for resident convenience. At one time, some manufacturers even offered a high security CBU option for those areas which require a bit more protection. However, the high security CBU was discontinued in early 2016. While the CBU models have parcel lockers built into each box, individual outdoor parcel lockers (OPL) were developed to increase the total amount of parcel lockers available within a single neighborhood installation. Just like the CBU, the OPL design has evolved over the years as well. The latest USPS approved design includes taller parcel compartments to better accommodate package sizes of today. In addition, to help “dress up” the CBU, some manufacturers have developed USPS Approved caps and pedestals. Available in various designs, these fashionable snap-together accessories place the final touches on the CBU so that it will complement the surrounding architecture. Only caps and pedestals which have been approved by the USPS can be added to the officially licensed CBU. [edit] Other Equipment Options The USPS created guidelines to dictate that wall-mounted vertical or horizontal wall-type boxes are to be specified in these settings. To represent the various levels of “approval” by the USPS, these wall-mounted mailboxes have been “rated”. Former approval standards were considered STD-4B+ and related to specific form factors and security levels of the mailbox. Today, STD-4B+ mailboxes are only USPS approved for replacing existing STD-4B+ applications. New USPS regulations related to wall-mounted, clustered type of mailboxes were introduced in 2004. These were the first changes to “apartment style” mailboxes in more than 30 years. This new regulation, STD-4C, replaces all previous regulations for mailboxes such as these, which were previously approved under STD-4B and STD-4B+. USPS Approved Manufacturers CBU Florence Manufacturing Company Postal Products Unlimited Inc.