The Vizio 55" 1080p LCD HDTV delivers full HD 120Hz picture quality and superior audio quality. This flat-screen model features a 120Hz refresh rate, SRS TruVolume and SRS TruSurround HD audio for advanced virtual surround sound, and a 100000 to 1 Dynamic Contrast Ratio. Three HDMI ports accommodate up to three HDMI devices. The Vizio 55" 1080p LCD HDTV also exceeds Energy Star 4.0 guidelines to reduce energy consumption and utilizes built-in ambient light sensing technology, which automatically adjusts backlight levels to the brightness of its surroundings.Note: You must have a source of HD programming in order to take full advantage of the Vizio 55" 1080p LCD HDTV. Contact your local cable or satellite TV service provider for details on how to upgrade.