Features: Battery free, mechanical energy self-powered, green and environmentally friendly. Stable signal, super penetrability, the farthest unobstructed working range up to 150M. 51 chord ringtones, 4 levels volume adjustment, 95dB maximum decibels. 110-260V wide voltage, sensitive and user-friendly, no wrong ringing. Long service life, button life up to 200,000 times. IP44 waterproof rating, windproof and rainproof. Premium flame retardant ABS material, secure and reliable. Suitable for apartments, high-rise residential buildings, hotels, factories, hospitals, and etc. Specification: Condition: Brand New Optional Type: Black US plug, black EU plug, blue US plug, blue EU plug Material: ABS Frequency: 315Mhz±0.5Mhz Receiver Voltage: AC 110V-260V Power consumption: <0.01W Working Range(open): 120-150m Chime: 51 ringtones Volume: 4 levels adjustable(including mute) Package Weight: Approx.169g/6.0oz Package List: 1 * Receiver 1 * Transmitter 1 * Screw Accessory 1 * User Manual 1、Battery free, mechanical energy self-powered, green and environmentally friendly. 2、Stable signal, super penetrability, the farthest unobstructed working range up to 150M. 3、51 chord ringtones, 4 levels volume adjustment, 95dB maximum decibels. 4、110-260V wide voltage, sensitive and user-friendly, no wrong ringing. 5、Long service life, button life up to 200,000 times.