1This smart electronic doorbell has an ultrawide angle of 145, which can greatly expand your field of vision. 2With the doorbell's not disturbing, taking pictures, video, selfstorage, PIR motion detection, human body induction and other functions. 3A variety of music ringtones can be selected, which can meet your needs and is a good helper in your life. 4Support door thickness 40110MM, suitable for door hole diameter 1550MM, can meet your needs. 5Press the doorbell button of the outdoor unit, and the indoor unit emits a dingdong bell to enter the monitoring state and take pictures. 6If you press the doorbell for a timeout, it will enter the standby state, which is very userfriendly. Item Type: Smart Door Viewer Material: ABS Colour: Black Usage: Family, Hotel, Villa, Apartment Battery: 4 x AA Battery (without Battery) Display: 3.5in High-Definition LED Screen Pixel: 720 HD Photo/video: Support Baiguang Night Vision: Support Storage: Maximum Support 32G Card (without Card) Support Door Thickness 40-110MM Suitable for Door Hole Diameter 15-50M 1 x Outdoor Machine 1 x Door Inside Machine 1 x Fixed Plate 6 x Screw 1 x Manual Battery is not included in our list.