What is the small white plate of Home Inn for?

Home Inn's small white square plate is used in the door lock system. This small disk is called a door card, which contains specific information and can interact with the door lock of a hotel room through contact or wireless technology. When a guest approaches the door lock with a key card, the door lock will read the information on the key card and verify its validity, and then open the room door. This door card system is usually used to control the access rights of rooms and provide security and convenience.