Vizio M55-D0 SmartCast 55&rdquo; Class 4K Ultra HD HDR Home Theater Display Resolution: 4K Ultra HD Effective Refresh Rate: 120Hz; Clear Action 360 HDMI Inputs: 4 VIZIO SmartCast w/ Google Cast Built-in Note: This is a tuner-free display. If you use an external antenna to watch local over-the-air broadcast TV signals, a TV tuner is required and sold separately.