TPE Wireless Doorbell with 900-feet, 52 Chimes, IP44 Waterproof Transmitter, 4-Level Volume 52 Different Ring tones. 4 levels of adjustable volume from 30dB to 110dB. Easy to add extra transmitter/Receivers. Support to add up to 10 transmitters. Plug receiver into a standard outlet in room (AC 110V US)/AC 220V (EU, UK, AU). CE, FCC, Rosh certified. Door bell operating range of 200~700 feet through the metal security doors and wall. Remote transmitter is rated IP44 Waterproof and acceptable for outdoor use. Transmitter designed with a message box. You can leave a message to your visitors or they can leave a note to you. Transmitter powered by 12V 23A battery, working temperature from -30 to 70.