Aigostar Wireless Doorbell with 36 Melodies and 3 Volume Levels, 150M/500Ft Range, 2 Battery Operated Receivers with Blue Light Indicator, and 1 Waterproof Transmitter. This doorbell is designed for easy installation without the hassle of cables. The transmitter is dustproof and waterproof, operating in temperatures from -20-60℃, and uses a 23A 12V alkaline battery with a maximum lifespan of 3 years. It features 36 stereo speaker chimes suitable for all users, with a memory function to preserve the last set melody and volume. The reliable 150M/500Ft wireless range ensures you'll be alerted when someone arrives. LED flash indicators are included for the hearing impaired or elderly. The package includes 2 battery-operated DC receivers, 1 transmitter, double-sided tape, and 1 23A 12V alkaline battery. Each doorbell undergoes rigorous testing to ensure quality and prevent issues.