[Long reliable range]Communication distance up to 100 meters (328 feet) (distance between sensor and receiver in open air) [Home security]The Wireless Home Alarm Security System is an easy-to-install and DIY home security system. When someone is near your home, the infrared sensor detects motion and sends a signal to the receiver, alerting you to someone. [Visual cue]When the infrared motion sensor detects any movement, the receiver emits an audible sound and the LED flashes; the LED flashes for visual changes. Your visual indicator is great when listening to music or hearing loss. [Wide range of applications]Used as a popular doorbell ringtone during the day and an anti-theft alarm system at night; it can be used as a walking path for doors, doorways, driveways, houses, homes, apartments, offices, hotels, shops and many other indoor venues. [Simple operation]Wireless installation, sensors can be installed , you can also place the sensor at the entrance. Name:Two with one Specifications: Type Options: 2 Receiver + 1 Transmitter Transmitter: 1x 6F-22 9V battery(Not included) Receiver Power: 2x AA batteries(Not included) Working Range: Up to 100 meters / 328 feet (open field) Transmitting Frequency: 433MHZ Infrared Sensing Distance: 3-7 meters Music: Classic Single "For " Receiver Size: . 9.3 x 6.8 x 3.7cm Transmitter Size: . 8.9 x 6.2 x 4.8cm Useful Tips: Do not place the detective in areas where the wind will move it. Also try to keep the detective in a clear path to the receiver, so that you can get optimal performance. Colour:white Material:plastic Package Contents: 2 * receivers 1 * transmitter 1 * accessory Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.