I use the same octo (when I have to) as Pete, figure it matches my yellow hoses. It's fairly common for the plug opposite the hose to be broken or missing, a 1/2 LP first stage port plug will work as a replacement.
If you don't mind crossing brands, the small Voit/AMF MR-2/Swimmaster/Titan seconds are a little smaller than the Conshelfs and really great breathing.
If you don't mind crossing brands, the small Voit/AMF MR-2/Swimmaster/Titan seconds are a little smaller than the Conshelfs and really great breathing.