Easy to install: Each door reinforcement lock is equipped with 4 long screws and 4 short screws, 8 screws in total, choose the correct one, and use an electric drill to install it in 5 minutes. Easily add an extra lock to your door. Easy to use: use your thumb and forefinger to press inside the circles at the top and bottom of the extra door lock, pull and flip to open, flip and push again to close. You can also see a live demo in our images. Safe and stable, no accidents - Improved design and high quality spring allow you to open and close the safety device of door safely and stably, and you can quickly open the device to leave the room in an emergency. PROTECTION FOR CHILDREN, LONELY WOMEN AND THE ELDERLY - The lock of heavy-duty additional door protects single women and the elderly from the outside world. It can also prevent young children from unlocking the door lock and going out without permission and getting lost.