uh...60 Hz? Seriously, it is the rate the signal is passed to the TV. Here is the THEORY: All USA power is at 60hz and the TV picks that up at the power input and syncs to the signal coming from the TV station. If you double that sync rate, theoretically, you would get a nicer picture with less video noise. However, there is much concern that this is a marketing gimmick. You even see 240 Mhz TV sets now. I could not see a real difference between 60 and 120Hz. Some people can see it. I am not an expert TV viewer, so you can take that for what it's worth. I suggest you go see them side-by-side.