... for multi apartments. 3.5"/4.0" color video door phone, 4.0" CRT video door phone, 2 ... materialScreen4"flat CRT, 3.5" or 4" TFT LCDAdjustmentsvolume,brightness,contrast,saturationInstallation methodsurface mountingSpecifications ... Color≤400mAMax. wiring distance80m/262feet(22AWG,4*0.5mm/2,4*0.75mm/2,Rvv4 cable)Wiring4wiresTalk time45~ ... /ODM available 3.5"/4.0" color video door phone entry system