The door security chain lock is designed to identify a caller before the door is fully released and prevent forced entry. Please request the discount code on the product page when purchasing to get a cheaper price. Allows the door to be opened at a distance of approximately 30 to 50 mm, providing great security to the outside. The structure made of heavy-duty steel makes it incredibly robust against violent intrusion to maintain security. Once installed, unlocking from the outside is no longer possible. The security lock provides reliable protection for hotels, hotels, doors, storage rooms, windows, etc. .