The reality is that it's a "throw away". Most people assume chains are interchangeable, but that's only true in a broad sense. Pitch is the only constant. Side plate thickness and pin diameter vary according the load rating. Then you've got O ring, X ring, T ring seals, no seals etc. Even the roller OD varies a bit.
So you should only replace chain parts with the exact parts from the same manufacturer. Sometimes the difference is only a few thousandths of an inch and you can get away with it in an emergency. Master links rarely interchange, so just because your buddy has one, doesn't mean that it will fit your chain. Not something you want to find out on the side of the trail.
Note that we are talking about motorcycle chain. Industrial chain is more consistant and interchangeable, but does not belong on a modern motorcycle.
Thanks, exactly the type of information I was looking for.