A super-hardy, bulletproof lock with few downsides
This lock is pretty-much bulletproof. If you’re looking for the strongest possible lock for your bike, this is the one to go for (perhaps coupled with a flyout cable so that you can tie your wheels together and to the lock). Note that this is a “short” D-lock, which is far safer, because a would-be thief can’t do the usual D-lock-breaking technique of using a car jack on it, very easily, but it also means that you’ll sometimes find it difficult to fit it around both your frame and the thing you want to lock your bike to. Also note that it’s very heavy, and that the mounting bracket doesn’t fit around the thickest of frames.
All in all, though, this is an ultra-hardy lock that should discourage all but the most-determined of criminals.