SMATRUL Self-Powered Doorbell, 2 transmitter + 1 receiver

【Self-Powered Doorbell】Neither the transmitter nor the receiver needs batteries, it will generate electric power by itself and send a signal to the receiver within a 490ft open distance when you press the transmit button.

【Waterproof Doorbell Kit】IP44 Waterproof Rated transmitter, operating between -4℉ and 122℉,  can withstand tough weather conditions more effectively.

【60 Ringtones & 5-Level Volume】60 ringtones for you to choose from, 5-level adjustable volume from 0dB to 110dB, perfect for classrooms, apartments, homes, villas or farms, making sure you never miss any visits.

【Easy to Install】After the transmitter and receiver are paired, you can fix the transmitter on the door or wall with stickers; or fix the transmitter with stickers or screws wherever you want.

【Not Just a Doorbell】It's not just a doorbell for notifications, it can also be a dog training doorbell, a call button for people with reduced mobility, and the LED flashing on the receiver makes it suitable for hearing impaired people too.