What type of locks prevent a burglar from breaking glass and unlocking the door from the inside?

Double key and double cylinder locks are designed to enhance security by requiring a key for access from both the inside and outside. This means that if a burglar attempts to break the glass nearby to reach in and unlock the door, they would not be able to do so without the key. The additional key necessity on the interior side acts as an effective deterrent against unauthorized entry through broken glass.

In contrast, single cylinder locks allow for easy operation from the inside, which can be exploited by someone who breaks the glass. Smart locks can offer various features for convenience and security but do not inherently prevent unauthorized access through a broken glass pane unless specifically designed for that purpose. Regular deadbolts, while providing a secure locking mechanism, typically operate with a single cylinder on the outside, which can still be compromised through glass breakage. Therefore, the mechanism of double key and double cylinder locks makes them particularly effective in scenarios where glass breakage is a concern.