Where can I find the serial number for Razer Kunai Chroma Triple Pack?

Hello.

I’m trying to register my Razer Kunai Chroma Triple Pack on the Razer website, and it asks for the serial number, part number, and purchase date.

I chave the part number and purchase date, but I can’t find the serial number anywhere (box or fans).

👉 Do these fans have a serial number? If not, what should I enter in the S/N field?

Thanks!