Quick LockThere is a steel ball embedded in a movable handle, providing smooth operation. It is a kind of improved alternative to replace door chain locks. When you need to lock quicklythe door safety guard in case of emergency, just move the swing bar to attach. Durable and SafeThe door security is made of premium zinc alloy, which is not easily broken and structurally deformed. The surface is polished and brushed nickel, which allows it to be anti-rust. Shewill always look new and will never be damaged or discolored. Child ProtectorOne of the important functions of this safety door chain restrictor is to protect children. Install the door safety guard high enough, where your children cannot reach, so that thechildren cannot open the front door and prevent strangers from breaking into the house. Wide ApplicationThe lock can open the door at a distance of 30-50mm approximately, which can see the outside with great security. Door restrictors allow you to identify visitors when it's not practical to have themto let in. You can also open the door slightly but lock it with a door security bar and ventilate the room. Suitable for Multiple OccasionsThe front door lock prevents forcible entry, such as bedroom door lock, window guard, front door chain lock, the patio door security lock, the door lockfrom hotel door, in storage rooms, veranda/patio and French doors etc.