Elertus Smart Sensor Alerts + Remote Temperature Monitoring System Remotely monitor temperature and doors from your phone, tablet, and computer. Perfect for monitoring your home, cabin, sheds, garages, and more. Connects to your existing Wi-Fi network. Elertus Smart Sensor measures: (1) Temperature; (2) Humidity; (3) Doors; (4) Light; (5) Movement. Receive 24/7 alerts to your phone, tablet, or computer. Temperature Range: -20F to 150F. Check status of temperature, humidity, doors, light, and movement from our Elertus app for IOS and Android. Customizable alerts sent through smartphone notifications, text message, and email. Elertus App for iPhone and Android devices lets you customize alerts. No subscription required. 2 AA Battery powered. Batteries included.