Kraken Pro Missing Serial Number

I have a Kraken Pro since oct/2018 and never used the Synapse or Cortex, but now i want to use it for gaming and while trying to register the product i found  a problem. The S/N (serial number) is visible on the left earcup, BUT the product number is not, soo i was wondering if there is a way of finding that number or maybe the support team could help me getting it? I can even send an image of what the numbers look like, but it's not very visible