RS-232 serial. It's super common when interfacing with test and measure equipment and with microcontrollers. Sometimes, you want a lot of them though, so instead of buying them online, you're best off making them yourself. Plus, these are a little nicer than what you can find online, and a little worse.
It's smaller, lighter, and USB type C, but it lacks some features like RTS, DIR, or CTS pins. It just has the bare necessitites. RX, TX, GND, ad VCC. Plus, it looks slick.
I'd wanted to sell these, but it doesn't make sense. Make them yourself, or integrate this circuit into your own projects.