It's all HDMI. So it comes with 1 HDMI cord and a USB cord. So, you'll need one HDMI cord to use it.
One HDMI goes from Xbox to Elgato, one goes from Elgato to TV. Then, the Elgato gets power from your computer through the USB cord. Only negative is, if your Computer is off you need a way to power it. But, I have my computer always on so it's no big deal to me.