Any idea what this particular joint is called in the industry? (see attachment)

I'm a product designer wanna be. I'd like to learn how to create this type of joint for a project I'm working on. If I have the name, I'll have the ability to do keyword searches and maybe the ability to see how it's created using a CAD program. Thanks in advance. Any help is appreciated.

This is part of a landing gear that I wanted from this platform, but the gentleman is in Poland which is experiencing some issues in the region with the Ukraine / Russia war going on so he may be unable to respond. So, I would like to build it.