Choosing the Right Locks and Physical Barriers

There are three main types of locks you'll see on storage units: disc locks, cylinder locks, and heavy-duty padlocks. Disc locks are the most secure option because the shackle is almost completely enclosed, making it really hard to get bolt cutters around it. Cylinder locks are similar and fit into a small hole on the latch, so there's nothing to grab onto. In general, you should look for locks with hardened steel bodies that resist sawing, shrouded or protected shackles that can't be easily accessed, and a good security rating from a trusted brand.
High-Security Padlocks
A good padlock needs a few things: a shackle that's tucked in so bolt cutters can't reach it, a steel body tough enough to resist drills and saws, and a lock cylinder that's hard to pick. If your facility isn't climate-controlled, get one with weatherproofing so it doesn't rust or seize up. You'll spend around $30 to $60, which feels like a lot for a lock, but it's nothing compared to what you'd lose if someone broke into your unit. Abloy, ABUS, and the nicer Master Lock models are all good bets.
Door Braces and Lock Boxes
For extra protection, some people add door braces or lock boxes on top of their main lock. A door brace is basically a metal bar that reinforces the door and makes it almost impossible to pry open, even if someone manages to cut the lock. Lock boxes cover your padlock entirely, so thieves can't get to it with bolt cutters in the first place.
These add-ons usually cost $50 to $100 or more, but if you're storing really valuable items or keeping things in storage for a long time, they're worth considering. Just make sure your facility allows them, since some places have rules about what you can attach to the unit doors.