House and apartment doors with glass inserts can be secured with this lockable door chain. Doors with glass inserts or narrow frame profiles can be protected from unauthorized entry using this lockable chain. The hardened special chain is particularly suitable for doors with glass inserts or narrow frame profiles due to its slim chain holder. The chain can be securely locked with a key and then opened only a crack, allowing you to always know who is at the door. A child safety feature protects the chain from curious little hands.