Has anyone used it?

[uefbv]

Does anyone know what this is used for? What are its main uses?

[FP91G]

Does anyone know what this is used for? What are its main uses?

Very bad photo, but it looks like a device for testing a board with chips from ASIC. It connects to the board from ASIC with chips for testing, diagnostic program on the laptop.

[ABCbits]

Does anyone know what this is used for? What are its main uses?

Using online reverse image, apparently it's called multifunctional/universal Antminer tester/test fixture. As implied by it's name, it's used to identify what kind of issue/error on your Antminer ASIC.