“A determined thief with an angle grinder and enough time can cut through nearly any lock,” says Master Lock's Justin Matuszek. “But more often, the thief has a bolt cutter and is trying to work fast.” He says the thicker a lock's shackle and the less it's exposed, the more secure the lock is from bolt cutters. And the kind of locking mechanism makes a difference in how easily a lock can be picked. The Master Lock Magnum
keyed padlock and the Master Lock ProSeries Combination Lock
both resist bolt cutters. Both are available at amazon.com. Plus, here's how to choose the best security chain.