Long Distance Range: Communication range of up to 100m in the open air (the distance from the sensors to the receiver) and detection range of the infrared sensor is approximately 30ft.Allow you an advanced and extra warning before guests(or intruders) arriveThe alarm ring in the receiver ranges from 90dB to 115dB.You can choose High Volume Chime/Low Volume ChimePower Supply (Receiver): 1.5 V C Battery x 3 OR 6V DC Adaptor (not included) ; Don't use them at the same time in case the host would be burned. Power Supply (PIR Transmitter): 9 V DC Batteries (not included) ;(For the best performance, please use fresh, high-quality, Alkaline batteries.)One transmitter can connect with 50 receivers at most, and one receiver also can connect with 50 transmitters at most.Do not place the detector 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.