 On April 19, 2004, a third version, marketed as the "AirPort Extreme Base Station (with Power over Ethernet and UL 2043)", was introduced that supports Power over Ethernet and complies to the UL 2043 specifications for safe usage in air handling spaces, such as above suspended ceilings.All three models support the Wireless Distribution System (WDS) standard.The model introduced in January 2007 does not have a corresponding PoE, UL-compliant variant.