Outdoor camera size: 3 x 3 x 7mm (1.18 x 1.18 x .28 inch) * Peephole size range: 13mm ~ 28mm ( .5 ~ 1.1 inch) * Door thickness range: 35mm ~ 1 5mm (1.38 ~ 4.13 inch) * Power supply: 3 x AA battery (not included) Voltage: 4.5 ~ 3.5V * smart door Peephole ,Door Bell,