PRODUCT APPLICATIONSEnhance your safety with our security door chain guard, designed for anti-theft doors, bedroom doors, apartment doors, rental room doors, dormitory doors, hotel doors, storage room doors, and sliding windows. It offers secondary protection against unauthorized entry while allowing for ventilation.PRODUCT DETAILS INCLUDE Material: Cold Rolled Steel Finish: Black Chain Specifications:Total Length: 187mm/7.36 inHole Diameter: 5mm/0.2 in Mounting Plates:Large Plate: 85.539mm/3.371.54 inSmall Plate: 5918mm/2.320.71 in Package Includes: 2Pcs Heavy Duty Door Chain LockPRODUCT ADVANTAGES1. This door lock chain is made of high-strength anti-rust cold rolled steel. The chain is thickened, the connection is tight, and the base is reinforced to enhance durability. The polished edges ensure smooth operation, are resistant to prying and pulling and provide long-lasting safety protection.2. The door chain can open some of the gaps in the door, which not only maintains ventilation and lighting but also prevents outsider from entering. It is suitable for safe conversation with visitors and leaves space for pets to enter and exit.INSTALLATIONThis chain lock for inside door is easy to install. It only needs to be fixed with screws(Mounting screws are not included). It can be installed at a height that children cannot reach to prevent them from opening the door by themselves.