Wireless MANs primarily use bridges with directional antennae to interconnect two or more networks over a metropolitan area. Point-to-point systems directly connect two sites; and point-to-multipoint enables multiple sites to connect through a central transceiver. Many companies utilize proprietary technologies for wireless MANs. Standards such as 802.11 and Wi-Fi enable less-expensive solutions, but potential RF interference persists. The 802.16 standard, however, promises to offer effective standards-based wireless MANs.