Quick Nauticam macro port question

I have a Nikon D7500 and housing, and have been shooting with both a Nikon 60mm lens, and a Nikon 85mm lens through a Nauticam Macro Port 60  (https://www.nauticam.com/products/macro-port-60).  In looking at the Nauticam port configuration chart, the 85mm lens states that a N120 Extension Ring 20 II is required.  I've been using the 85 without the extension ring with no issues.  Is there a reason/benefit as to why I should/need to add it?

Ok…. Please disregard. I don’t actually have a Nauticam Macro Port 60 …. It is a Compact Port 30 with a compact base port added…. Now all makes sense.