Bike thieves should beware of the Kryptonite Evolution Series 4 1090 Chain Lock. With 10-millimeter, 6-sided chain links made from 3T Manganese steel, it's anything but easy to break. This burly lock can secure your pride and joy with confidence, and it won't scratch your frame in the process thanks to its durable, weather resistant nylon sleeve. The Evolution Series 4 1090 features an End Link Design that secures the chain to a hardened deadbolt to eliminate critical vulnerability at the end of its links, and uses a pick-and-drill-resistant high security disc-style cylinder. Kryptonite is so confident in the Evolution Series 4 1090 chain lock that it gives it a whopping 8 out of 10 on their security scale, and stands behind it with their Anti-Theft Protection to help you recover if anything happens to your trusty steed while it's locked up.