Kraken X Activation code

I can't find the activation code to my new Kraken X headphones to use the 7.1 surround sound app. I also tried to register my product as it said on the help page, but the problem is I can only find the serial number and I can't find my product number anywhere. The help page was in-accurate of showing where I can find the product number. Why is this so hard to find? Do I need to take something off from the headset or where is it?