Yale E-SD2 Smoke DetectorThe Yale Smoke Detector is a battery operated device, 9V battery included, which enables it to be easily installed (DIY) in any room without the hassles of running wires, calling an electrician or a handyman. Protect your family by using Yale Smoke Detectors in your home to alert you of any potential fire threats Battery operated (1 x ‘9V’ included) 85dB Siren.Non radioactive photoelectric sensor, designed to alert you and your family to the presence of smoke.Low power consumption. Operated by a 9v batteryfor more than 1year.Easy installation. No external poer supply and no wiring is required.External test button on the cover for easy testing.No interference between smoke detectors if more than one device is installed.Unlimited number of devices can be installed in one dwelling.specification:Alarm Range: 30mOperating Frequency: 868Mhz