ALARM DOOR COMPATIBLE WITH ALEXA,GOOGLE HOME: No hub needed. Smart door window alarm supports WiFi connection and it works with Alexa Google Home. Support voice control by Google and Alexa. GREAT FOR YOUR TODDLERS AND ELDERLY PEOPLE: With door open sensor alarm, you don't have to worry about your little ones going out of house without notice, and easily know when your elderly parents leave or arrive home, even can be clear when someone enters your house, store, office, etc You can check your home on APP wherever you are. WIRELESS MAGNETIC SENSOR -- EASY INSTALLATION: Easily setup WiFi window alarms for home in minutes - without tools or professional installation, you just tear off the tape on the sensor door, stick it on your target position. Whether you're at home or on the go, the smart WiFi contact sensor will push notification to alert you when the door/window is opened or closed. LOW ENERGY CONSUMPTION and DURABLE PERFORMANCE: door open alert Wireless door sensor is supplied by 2 * AAA micro batteries, working time can last for one years without replacing the battery. When the battery is low, the APP interface will display low battery (Does not include battery). Please note that due to manual measurements and display differences, there may be slight differences between individual products and photos.