Feature:1. No Battery Required: Self generating wireless doorbell, wiring free, battery free, long distance transmission, two doorbells and one receiver, can be used for front and rear doors.2. Long Operating Range: Strong penetration, the transmission distance is greater than 150m without blocking, it is always easy to be notified when someone calls from the door.3. 38 Ringtones: There are 38 optional ringtones, it can emit rich, clear and stereo sound. There are 4 adjustable levels, and the indicator light is also easy to notice.4. Material: Premium materials to prevent from being affected by higher temperatures and interference. Could withstands various severe weather conditions, suitable for indoor and outdoor use.5. Multifunctional: It can not only be used as a doorbell, but also as a pager, suitable for babies, the elderly, pregnant women, convenient for the elderly and patients.Specification:Item Type: Wireless Doorbell SetMaterial: ABSPower Supply: Self generatingTransmission Distance: 150m/492ft (Without blocking)RF Frequency: 433MHzRingtones: 38 (4 adjustable)Ringtone Volume: 50dB/(1m/39.37in).Uses: Can be used in homes, villas, hotels, factories, the elderly, the sick, pregnant womenPackage List:2 x Doorbell1 x Receiver2 x Sticker1 x ManualNote:Please follow the use voltage for power supply, the use of other voltages can easily cause fire and product damage!