Ankuoo REC Self-Powered Wireless Doorbell, No Battery Required For Transmitter Or Receiver, White Never buy batteries again: self-powered, no battery required for transmitter (remote) or receiver (doorbell) Operates using kinetic energy, self-contained, relying solely on human input to trigger, no maintenance cost Instant installation and location flexibility 4 adjustable volumes; 38 ringtones; ultra-light-pressure trigger; waterproof for outdoor usage; 100 feet range Package includes: self-powered transmitter (1), receiver (1), user manual, plastic wall mount, mounting pad, wall mount screws