- The stainless steel chain door lock is made of HQ stainless steel with high hardness, corrosion resistance and rust resistance. Main body length 5 inches; chain length 6.7 inches; material thickness 1/16 inch. All components are stainless steel for strength and durability. - Anti-theft design with a spring anti-theft push lock provides better security and helps prevent intrusion. Includes additional locking devices for the front door and inner door to protect your family. The inner door security lock and front door chain lock can also be used to secure your space or allow small pets to enter and exit. - Hand-brushed surface treatment for a pure, beautiful appearance. Resists rust and extends service life. Optional finishes available in brushed nickel, matte black, red bronze, gold and bronze to match modern home decor. - Vision and ventilation safety: heavy-duty chain lock allows the door to remain clearly visible and ventilated when partially open, while providing additional security for residential and office doors. It cannot be unlocked from the outside, ensuring safety. - Specifications at a glance: main body 5 inches; chain 6.7 inches; thickness 1/16 inch; manufactured from HQ stainless steel. - Use scenarios: ideal for homes with children or pets needing a secure yet partial opening; suitable for apartment entry doors where occupants want visibility and airflow; useful for office doors requiring controlled access while maintaining ventilation and security.