What is it?

wingnut-tightened nipple pinchers or sexual bondage tools


Obviously, it's some kind of clamp.

 

They aren't clamps per say. Both of them are needed to accomplish their task, a third would not be necessary and might possibly get in the way if one tried to use an extra.

 

It can't be used for a hose.

 

They are indeed centering cones, but this pair is made for a different purpose.

 

Trees?

 

Nothing to do with trees.

 

The centering cones are just a feature. The cones center the object itself to something else so it can do what it is meant to do.