If you are looking for the "little guy" of the original Elgato Game Capture HD60, that is a Mini USB cable.

https://www.amazon.com/AmazonBasics-USB-2-0-Cable-Male/dp/B00NH11N5A

It's just a regular USB-A to USB-B MINI cable. You should be able to find one almost anywhere, but for good measure, here's a link to amazon https://www.amazon.com/Amazon-Basics-Charging-Transfer-Gold-Plated/dp/B00NH11N5A