Features:  NO BATTERY REQUIRED: Door transmitter is used the unique Kin etic technology that generates electric power to ring your home doorbell without any battery and create wireless signal.  50 M/164-FT WIRELESS RANGE: 1 receivers included; will not interfere with other equipment in your home or those of your neighbors; ensures that you will never miss any visitors, even if you are several rooms away.  28 MELODIOUS CHIMES: 40 mm stereo speaker delivers rich and crisp sound; 4 adjustable volume levels with a maximum volume of 110 dB; press Next or Previous button to easily choose from 28 melodies and you will enjoy pleasant melodies whenever someone rings at your door.  IP68 WATERPROOF: IP68 dustproof and waterproof rating; works between -10 °C to 55 °C; withstands various harsh weather conditions, MEMORY FUNCTION: Preserves your last-set melody and volume level after a power outage; no need to reset to your previous settings; convenient and easy-to-use design for an enhanced user experience.  EASY TO SET UP: Just plug the mini receiver into a socket and fix the transmitter on a wall with the accessories provided; includes Double-sided adhesive tape.  Specification:  Power consumption: 0.1W.  Power Supply:Receiver(AC 110-120V/220-240V).  Transmission distance: 164ft / 50m maximum effective range.  Waterproop: IP68 weatherproof & dustproof.  Working temperature: -10°C to 55°C(Receiver) /-20°C to 65°C(Transmitter ).  Volume: 25-110dB.  Working frequency: 433.92MHz+200KHz.  Package included:  1 x Transmitter.  1 x Wireless Doorbell.  1 x Adhesive patch.  1 x User Manual