High quality external chain
 

1 the chain in the platform must high weight, want to find some weight high place to send the chain.
2 in the high weight place surrender of the document of reverse connection, instead of links.
3 the chain of endurance, not hair today, and tomorrow is gone.
4 the chain can bring the conversion rate and the user's transfer rate, let the other people to help us do the chain, the outer chain is fine.