The shackle is the most exposed part of a padlock. As a vulnerable point on an otherwise wholly secure design, padlock manufacturers generally use a sturdy material to prevent damage. Shackle material types can include brass, stainless steel, hardened steel, hardened boron steel alloy, boron carbide, and molybdenum steel alloy.
Brass and stainless steel are lower quality options that offer minimal protection against impact, though stainless steel shackles are outdoor rated due to its corrosion resistance.
Removable Core A removable core is excellent if you are looking for a padlock for a rental facility or storage container. You can change the center of the lock, without having to replace the lock itself. The core of the lock is the internal mechanism that contains the pins and the drum. To remove the core, you need a master key, which pushes a locking pin into an alternate shear line that disengages it from the lock, instead of turning the drum within the core. Reasons you’d want to replace a core include those that are damaged or tampered with, ones that correspond to a key belonging to a renter, who has recently given up their rental or was evicted. This ensures someone can’t use a duplicate key to re-enter the premises, and you don’t have to purchase a new lock every time you rent a space for a new person.
The bigger the lock, the more secure it is because thicker metals are more resistant to breaking. Also, larger lock bodies provide more space for additional pins or internal safety features, and internal locking mechanisms can also be larger and more robust.
However, there is one significant downside to a large lock: The weight.