1. Security and data protection: The security lock comes with a carry bag, allowing you to place it in a bag or handbag for use during hotel stays or other shortterm rentals. When you are asleep, no one outside can open the door with a key, significantly enhancing your safety. 2. Easy to use: The portable security door lock can be quickly installed and removed without tools or drilling, making it an essential travel safety accessory. First, open the door and insert the metal piece into the door lock slot. Second, close the door and place the red handle groove onto the bolt of the metal piece—installation is complete. 3. Widely used: for motels, hotels, resorts, dormitories, apartment security, shortterm rentals, bathrooms, bedrooms, etc. It can also prevent pets from going out or children from opening doors for strangers. The door lock provides secondary protection, but you should still lock your door and not rely solely on it. 4. Portable door locks: Suitable for inwardopening doors with hinges and a proper door seal (door seal ≥ 3 mm). The improved locks come in two sizes for different door holes: 0.87 x 0.78inch door hole; 1.18 x 0.78inch door hole (please measure your door size). Not suitable for sliding doors, double doors, slatted doors, or swing doors.