Video door phone,door knocker,viewer knocker,hot product Operation humidity 10-90% Door thickness 25-65 mm (1-2.5) Video door phone,door knocker,viewer knocker,hot product ... 21 mm (1.5 x 3 x 0.8 in) LCD Screen TFT color type, 115,200 pixel Screen Size (W ... ) Spy Hole Diameter 14 mm (9/6in) or 23 mm (7/8 in) Video door phone,door knocker,viewer knocker,hot product