A peephole is required in order to install the device, easy setup, voice massage-leaving feature, Photo-taking & browsing function 2.Pin-hole camera on outdoor unit, you can see the visitor from the screen instead of traditional peephole. 3. 2.4TFT high definition screen with low power consumption, no radiation, ultra thing indoor unit leads the fashion trend. 4. Damage-proof, water-proof, oxidation-proof and abrasion-proof panel outdoor unit. 5 Powered by 3 AA batteries, no power consumption under standby mode.