No, those are just 77mm/80mm OD threaded metal rings screwed on step-up rings, it makes the setup sturdier, it is much easier to put filters on comparing to thin filmsy stepup rings, and they add some distance from follow focus to hood/mattebox. I found them by accident in those cheap Chinese collapsible rubber lens hoods, bought bunch of them and threw away the rubber part ;) and my setup is comparable in functionality to the part that proffesional cine-modding shops add on the lens, just for a fraction of the cost.
PS those Xume adapters seem cool, never seen that before
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