The collar is a symbol, it belongs to the Dominant but the submissive gets to wear it as a symbol of their ownership. It is usually the most important piece of jewelry worn on a daily basis. A collar for submissives is one of the most fundamental symbols of their relationship and one that is usually guarded and protected with their heart.That collar also works as a symbol of Dominance for the one who gave it, right? So, in effect, the collar works as a relationship symbol and not one side or the other. Ask any Dominant what the collar means, and it will mean ownership - to them.
The O-ring symbol has long been a representation for an abstract concept describing something without limits