@flitecontrol - Sorry, I didn't post the image right away. It's a different diagram. The one you refer to doesn't list out the o-ring separately, this one does.
I'ts for an adjustment valve of some sort. I have not idea what it's called. Please look at the pic I just added to my post.
your exploded view is from aftermarket printer describing each and every item..
Honda on the other hand would make no money handling individual o-ring or other small part if it can be included (and generally used together) repairing a unit..
Thus they sell assemblies, $$$ which are shown in parts fiche as such..