Master Lock Pro Series Locks are High Security Padlocks that Feature Hardened Boron Alloy Shackles for Superior Cut Resistance, Dual Ball Bearing Locking to Resist Prying and Pick-Proof Cylinders. Other Pro Series Security Features Include Hidden Shackles, Iron Shrouded Shackles & Weather Tough Coating for Harsh Outdoor Conditions. Shop Like a Pro Today at The Lock Source!