Feature:1. Battery Free: Self generating doorbell, wiring free, battery free, long distance transmission, equipped with two doorbells and one receiver, can be used for front and rear doors.2. Long Distance Transmission: Strong penetration, signal matching, no about crossing line. Whether you use it in a few rooms away, it is always easy to be notified when someone calls from the door.3. Ringtones: There are 58 optional ringtones, and the built in speaker can emit rich, clear and stereo sound. There are 4 adjustable levels of volume, and the flashing indicator light is easy to notice.4. IP44 Waterproof: Made of premium materials, prevents itself from being affected by higher temperatures and interference. Could withstands various severe weather conditions, suitable for indoor and outdoor use.5. Multiple Use: It can not only be used as a doorbell, but also as a pager, suitable for babies, the elderly, pregnant women, sound and light reminders, convenient for the elderly and ear disease patients.Specification:IItem Type: Self Generating DoorbellMaterial: ABSTransmitter Power Supply: Self generatingTransmitter Size: Approx. 63 x 63 x 20mm/2.48 x 2.48 x 0.79inTransmitter Working Temperature: -20C to +60CTransmitter Transmission Distance: Open places larger than apprrox. 150m/492ftTransmitter RF Frequency: 433MHzReceiver Power Supply: AC110-240V 50/60HzReceiver Power Consumption: 0.25WRingtones: 58Receiver Volume: 90dBReceiver Working Temperature: -10 to +45.Package List:2 x Push Button1 x Receiver2 x Sticker1 x Manual