features 38 doorbell chimes, 4 adjustable volume levels and CD quality sound. It can be conveniently used in homes, offices, factories and more. Features Self-Powered Transmitter Adopt advanced technology to convert kinetic energy into electricity and transmit wireless signals to the receiver. No battery is required. No hassle in buying or changing batteries. Reliable Durable The durable push button can be used around 200,000 times. With an impressive IPX7 waterproof rating, the transmitter can withstand harsh and wet weather conditions. Wireless Transmission Support a wide wireless operating range of up to 262ft in open areas. Get instant audio and visual alerts when visitors press the button on the transmitter. Never miss a visitor again. Customize Your Doorbell The receiver offers 38 optional chimes and 4 adjustable volume levels (up to 105 dB) to suit your needs. User-friendly Flashing LED indicators on both the transmitter and the receiver provide a visible indicator in a noisy environment or for the hard-of-hearing. Easy and Safe The absence of wires makes the setup simple and hassle-free, safe and reliable. No pairing required. Ready to go out of box. Versatile Triggering the signal transmission only requires a very tiny pressure of 350g. It can be conveniently used by patients, the elderly or children to page or contact their loved ones and care takers. Expandable You can expand each receiver with multiple push buttons or multiple receivers for one push button. And each receiver can be configured with different chimes and volume levels.