Cobra links use to offer to pay your deductable if your bike was stolen but I am unsure if they still make the product or not. It is not so much a chain, but a solid coiled tempered steel cable that is about 1-1.5" thick with a tubular lock. It is heavy-about 30 pounds for the 6' long "cable".
The thing to keep in mind-any lock only keeps and honest person honest. If a thief wants your bike, it is toast. In the case of Cobra links, they would just cut the frame of the bike,bend the frame tube slightly to remove the cobra link and then remove the bike from the area, leaving the cobra link locked to what ever immovable object the bike had been locked to.
