Features: Mechanical energy self-generating electricity, 110-260V wide voltage. IP44 waterproof, highly sensitive and easy to use, no mistakes. 51 chord music ringtones, four levels volume adjustable, ringing sound up to 95dB decibels. Strong signal, super penetration, long unobstructed working distance up to 150M. Strict quality testing, button life up to 200,000 times, which can be used for 20 years pressed every 28 times one day. High quality flame-retardant ABS material, no burning at high temperature, safe and reliable. Broad application to apartment, high-rise flats, duplex unit, hotel, factory, hospital, and etc. Specification: Condition: Brand New Material: ABS Optional Type: White US Plug, White EU Plug, Black US Plug, Black EU Plug Frequency: 315Mhz0.5Mhz Power Consumption: 0.01W Receiver Voltage: AC 110V-260V Working Range(open): 120-150m Volume: 4 levels (including mute) Package Weight: Approx.209g/7.4oz Package List: 1 * Transmitter 1 * Receiver 1 * Screw Pack 1 * Tape 1 * User Manual 1Mechanical energy self-generating electricity, 110-260V wide voltage. 2IP44 waterproof, highly sensitive and easy to use, no mistakes. 351 chord music ringtones, four levels volume adjustable, ringing sound up to 95dB decibels. 4Strong signal, super penetration, long unobstructed working distance up to 150M. 5Strict quality testing, button life up to 200,000 times, which can be used for 20 years pressed every 28 times one day.