1User Friendly: When the visitor presses the bell button, the device will automatically turn on and take a photo. 2Wide Angle: HD camera and 90degree wideangle lens provide clear images for your front door. 3Night Vision Lights: When the light is insufficient, the infrared night vision mode will automatically turn on, ensuring that visitors can be clearly seen even in the dark night. 4Cyclic Storage: The internal memory can store up to 75 latest photos and automatically overwrite the oldest photos. 5Easy Operation: Humanized button design, easy operation for the elderly and children. Item Type: Door Viewer Material: ABS+Zinc Alloy Use: Household Battery: 3.7V lithium battery 800mah (built-in battery) USB Power Supply: DC5V Screen Size: 2.8in Screen Resolution: 320 x 240 Camera Pixel: 0.3MP Infrared Light: 2pcs 850nm Viewing Angle: 90 degrees Storage Method: Self-contained memory, cyclic storage Applicable Door Hole Diameter: Approx. 14-22mm/0.55-0.87in Applicable Door Thickness: Approx. 35-120mm/1.38-4.72in Use Environment: -20-55 1 x Inner Door Machine 1 x Outer Door Viewer 1 x Fixed Plate 3 x Screw 1 x USB Cable 1 x Manual