Model: HK912  

1. The door lock adopts a two-stage locking mechanism, consisting of a standard lock and a special lock. The standard lock cylinder is spring-loaded, while the special lock cylinder is not.  

2. The interior side of the door lock is equipped with a rotating handle, and the keyhole is a 9×9 square hole.  

3. The exterior side of the door lock features a fixed handle, and the keyhole is a 9×9 square hole.