Sometimes you have a stack of old parts and you need for example a camshaft chain. Now how can you optically determine which one is usable?
The one marked "New" is one i found without a wrapper, so i think it is a NOS chain for the camshaft of the Honda PS50.
The chain marked with A is the one that came out of the engine block that i am restoring. You can see that you can bend the chain sideways more than the new chain.
The chains marked with B are definitely worn out. They can bend much further even than chain A. Also, if the chain-links them self show a lot of space in between the so-called "8" parts and when it rattles, the chain may be worn out too. And always check for dents in the rollers!