Stop wondering if you closed all your windows after leaving home. Check on your doors and windows at a glance with the Tapo app. Tapo Hub required - connects to the Tapo H100 hub (sold seperately)Set your Smart Contact Sensor to trigger on the lights when you open your door. Receive instant alerts on your phone when a door or window is opened unexpectedly. The Hub can sound a siren to warn of danger and deter intruders.2-year battery life provides long-lasting convenience. Receive notifications from the Tapo app when the batteries are low and need changing. Place it wherever you need with our tool-less installation. The gap between the sensor and magnet (up to 15 mm) fits most doors, windows, and other fixtures. Experience your next-level smart home with the Tapo app. Create a more secure, convenient, and comfortable living space for you and your loved ones.