The Micro Saver lock head features the patented T-bar locking mechanism. The T-bar provides a tight fit with the Kensington Security Slot. A rubber bumper ensures a snug fit between the lock & the security slot & protects your hardware. A further deterrent is the tamper evident feature. When a Kensington Micro Saver lock is tampered with, it locks itself down & can even trap foreign keys. All Kensington locks are built to exacting engineering standards. This lock is rated as Safe Pro, a rating awarded to Kensington Security Locks that are tested under stringent test conditions by third party testing agencies for their ability to withstand attacks. We provide two keys with each standard lock. Each key is stamped with a unique code. Register your code online & well be able to send you a replacement key. Our business is protecting yours Kensington locks are made with high-carbon steel cables & tested under rigorous real-world conditions to resist lock-picking, corro.