Designed to survive the bike-thief-plagued streets of New York City, this 9.5-pound lock features fat 15mm links forged from 3T steel. The chain resisted our hacksaw and cutters but gave in to the grinder after 2:30 and a spray of sparks. Serious defense, but it's heavy, and we wish it were longer – the three-foot chain was difficult to lock on a bike and impossible to latch around a waist. [$175;]