North Carolina Locksmith Practice Exam

What feature helps improve security in a double cylinder lock?

1. It has a keypad for entry

2. It allows key operation from both sides

3. It is made of reinforced steel

4. It has a hidden keyhole

The correct answer is: It allows key operation from both sides

A double cylinder lock enhances security primarily because it allows for key operation from both sides of the lock. This design is particularly beneficial when doors have glass panels or are located near windows. In such scenarios, an intruder could potentially break the glass and reach in to unlock a single cylinder lock, which typically operates with a key on one side and a thumb turn on the other. However, since a double cylinder lock requires a key to operate from both sides, it significantly reduces the risk of unauthorized entry via glass breakage. The other features listed, such as keypads, reinforced materials, or hidden keyholes, can certainly contribute to a lock's security but do not directly relate to the specific functionality of a double cylinder lock. Keypads provide convenient access control, reinforced steel adds strength against physical attacks, and hidden keyholes offer stealth against tampering. However, the unique mechanism of needing a key to unlock from both sides is what distinctly classifies a double cylinder lock as a more secure option in certain vulnerable situations.