What on earth *is* this set up?

[M DeM]

Can anyone tell me what the big lens-looking circle is in the middle of the arms? Site doesn't say.

 

[RVBldr]

Lens holder with a lens it appears.

 

[Furnari]

It's holder for a wet lens so you have a safe place to store it if you take it off the front of the port:
Lens Holder for 67mm Threaded Lenses

 

[Dan]

I no longer use long arm with a strobe, instead I use short arms with 10,000-lumen video-lights for taking still picture & video. So I move my wide-angle wet-lens holder to power inflator hose.

 

[M DeM]

Very cool! Thanks for the info!