T2 adapter, which allows you to attach your Sony camera to a telescope or astronomical telescope with a T2 mount, for example.

T2 adapter that allows you to attach Sony E and FE mount mirrorless system cameras to any T2 (T-Mount) mount.
Most commonly, this is used to attach a camera to a telescope or stargazing telescope, allowing the telescope to truly act as a telephoto lens.
The T2 adapter is screwed onto the T2 thread of the optic/accessory. The camera body is attached to the other end of the adapter.
Camera mount: Sony E and FE
Lens mount: T2