1. This products is widely used in hallway, gangway of enterprise, hotel, home, supermarket & warehouse, ect. 2. One of the music has designed in Dingdong, double dingdong, 12songs, west minister. 3. Use DC power, sender use 1pc 23A 12V; Receiver use 2pcs AA batteries; 4. Remote distance: About 30 meters; 5. Frequency: 433. 92MHz; 6. The sender is waterproof; 7. With digital codes to avoid disturb
