Features: 1. Press the button, super learning code can freely learn to match, can be unlimited matching receiver and button. 2. The transmitter without screw chuck design to achieve waterproof and dustproof. 3. The transmitter USE a 23A12V alkaline battery (not included battery). 4. Receiving distance:300 meters in open area. 5. The wireless signal will be affected by obstacles. The more obstacles, the more serious the signal loss. 6. Receiver has 6 levels(can be mute) 0-80db,48 music to choose from. 7. Transmitter size:79*45*22mm. 8. Receiver size:100*57*25mm. 9. Just plug the receiver into an electrical outlet,the push button transmitter can be stick it to the door with provided adhesive tapes. Note: The button cannot be placed on an iron door because it will interfere with the signal. If the receiver does not ring when you press the button after receiving the doorbell, please check the steps: 1. Please confirm whether the button has a 23A12V alkaline battery installed. 2.Check if the receiver has a 3*AA alkaline battery installed. 3. Please pair the doorbells again. How to pair signals? Press the receiver's music button for about 5 seconds. After the receiver light flashes, press the transmitter again. The pairing is successful. The button uses a 12V23A alkaline battery. Package includeds: 1 x Transmitter. 2 x Receiver (Battery Included.)