Features: 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 Set_x000D_ Material: ABS_x000D_ Power Supply: Self generating_x000D_ Transmission Distance: 150m/492ft (Without blocking)_x000D_ RF Frequency: 433MHz_x000D_ Receiver Power supply: AC110-230V_x000D_ Ringtones: 38 (4 adjustable)_x000D_ Ringtone Volume: 50dB/(1m/39.37in)_x000D_ Uses: Can be used in homes, villas, hotels, factories, the elderly, the sick, pregnant women PackageList: 2 x Doorbell 1 x Receiver 2 x Sticker 1 x Manual Note: Please follow the use voltage for power supply, the use of other voltages can easily cause fire and product damage!