Tukzer Digital Door Viewer with 2.2" LCD Screen Monitor, Battery-operated and Non-remote Video Peephole Viewer 1.Digital electronic peephole, also called electronic door viewer 2.The peephole viewer attached to anti-theft door consists of two concave and convex lens 3.Only need 5 minutes to DIY install 4.Low power reminder function: When the battery is in low volume, the indicator at the right bottom of screen will light up, which indicates that we should change battery immediately 5.User-friendly principle, even senior user with poor eyesight or little kids can easily operate the door peephole viewer