Question about Inon Z240 ball arm

I recently bought a used Z240, and had a question about the ball arm attachment.

Does anyone know why is there an o-ring on the ball arm attachment? I'm referring to the o-ring between the ball arm attachment and the strobe. It makes no real sense to me as there's nothing being sealed. It's only purpose seems to be a cushion of sorts between the ball arm and the strobe.

I imagine its a type of lock washer, keeping tension on the screw so it doesn't wiggle loose.

Possibly provides additional friction to help keep the screw thread tight?