Volume: high, medium and low, 3 levels of volume adjustment Ringtones: 6 ringtones Built-in battery: 800 mAh indoors, 800 mAh outdoors Call distance: up to 500 meters in open areas outdoors Call: 1 to 10, answering can only be one-to-one USB interface: Type-C/DC5V-1A Installation method: wireless installation, simple and convenient Use scenarios: home, restaurant, villa, company, courtyard, etc. Colour:black Material:ABS Package Contents: 1 * Doorbell 1 * Receiver Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.