The door security chain latch is designed to identify a caller before the door is fully released and to prevent forced entry;When you buy, please get the discount code on the product page to get a more favorable price.Allows the door to open to a gap of about 30-50mm providing great security from the outside;Heavy duty steel structure makes it incredibly robust against violent entry to maintain security;No drilling or chiseling required for installation. After installation, it cannot be unlocked from the outside.The security lock provides reliable protection for hotels, hotels, doors, storage rooms, windows, etc.