Feature:1. Self Powered Doorbell: When the finger presses the doorbell, the kinetic energy is converted into electrical energy, 2pcs doorbell used for rear and front doors.2. 150m Range: The doorbell adopts 433MHz wireless signal, which has super penetrating power, and the receiving distance in open areas can reach 150m.3. 38 Melodies 3 Volumes: 38 melodies can be switched freely, the ringtones are pleasant to the ear, 3 volume adjustable, and mute can also be set.4. Waterproof: The waterproof level of the transmitter reaches IP44, it can be installed outdoors and indoors, and is safe to use in rainy and foggy weather.5. Nursing Pager: Not only a doorbell, but also a caregiver pager, suitable for the elderly, patients, pregnant women, guarding your family members.6. Installation Method: Including strong double sided tape, no need for wiring and no damage to the wall, you can also use screws to install the doorbell.Specification:Item Type: Battery Free Wireless DoorbellMaterial: ABSOperating Frequency: 433.92MHzStandby Power Consumption: 0.25WRingtones: 38Volume: 3 Levels + MuteControllable Volume: 50dB/1mReceiving Distance: 150m / 164yd (In Open Space)Receiver Working Temperature: -10-+45Transmitter Operating Temperature: -20-+60Receiver Size: Approx. 78x54x20mm / 3.1x2.1x0.8inTransmitter Size: Approx. 66x40x20mm / 2.6x1.6x0.8inBattery Free: The transmitter does not need a battery, it is self generated by pressing.Package List:2 x Doorbell1 x Receiver2 x StickerNote:1. The remote control distance is affected by the use environment, and the distance will vary due to different use environments2. When using wireless electronic products, you should avoid large electronic equipment, electromagnetic fields and other strong sources of interference, so as to avoid the remote control and the receiving distance being short or unable to work normally.3. Do not use this electronic product abnormally. Abnormal use will reduce the performance and life of the product. In severe cases, it will damage the product and bring potential dangers to your safety.