Feature●The smart opening and closing sensor allows you to check the door opening and closing even when you are on the go●No hub required, just plug the product into the router. You can register to the smart life app, so you can link it with your camera and more●Compact design that attaches to windows, refrigerators, and first aid kits. It will notify you even if the lid is removed, so you can rest assured of security●Accessories: 2 AAA alkaline batteries, adhesive sheet, reset pinDescription The smart opening and closing sensor allows you to check the door opening and closing even when you are on the go. No hub required, just plug the product into the router. You can register to the smart life app, so you can link it with your camera and more.