Product Material: The door chain is made of stainless steel, not easy to break, not easy to age rust, use longer. Make home safer: Lock-in-lock design, door chain with its own spring anti- theft pressure lock, only indoors can open the chain to avoid theft or forced entry, providing security for you and your family. Installed in high places can prevent children from accidentally running out. durable: This product uses thicker chain, chain torsion welding combination is tight, not easy to break, strong and durable. Easy to install: The door chain lock is matched with four screws, which can be installed where needed. The product is suitable for all kinds of wooden doors, and can also be drilled on iron doors for use. The use of a variety of occasions, can be used in homes, hotels and other places. Caution: This product requires drilling during installation, which will cause damage to the wall and door, please purchase as needed