When looking for an essential component of your home security system the DS1 2-pack is exactly that. The Xodo DS2 4-Pack Wi-Fi Security Smart Wireless Alarm Door Sensor improves the security in your home or work place. With its own magnetic sensor switch that detects your door or window opening, at 120 DB you can be sure to be alerted effectively whether you are asleep or in another area where the movement is happening. With an easy and convenient installation, this device also makes an excellent alarm in case other activity is occurring without your supervision. This device is compatible with Amazon Alexa and Google Assistant. The Xodo DS2 4-Pack Wi-Fi Security Smart Wireless Alarm Door Sensor is controlled and armed from your free Xodo App at the touch of a button giving you access to control your alarm when you are away from your home or work place. The Xodo Smart App allows you to use different functions which includes the option to alter your settings for incoming alerts with push notifications to obtain and follow past history alerts and the ability to disarm your alarm with a press of a button in your Xodo Smart App. This product requires a 433 mhz receiver hub which connects to WiFi. Xodo Smart Hub SA2 is sold separately. Locations are identified for each sensor installed by name in your App whether it be at your front door or back door and even windows.