Motion Alarm: Designed to suit your specific security needs, this motion sensor has an alarm system that alerts in response to any movement. | Easy to Install Anywhere: Motion Sensor and alarm units are battery operated (Batteries not included). | Scalable Design: The alarm system for home security is wireless and up to 50 door sensors can be linked. | Wireless Alarm System: With a transmission range of up to 390 feet and a detection range of up to 26 feet, this motion alarm sensor with LEDs can be used indoors or outdoors if it's protected from the elements. | Set Includes: This security alarm system includes 1 PIR motion sensor unit and an alarm unit