intercom,inspection and unlock.support two camera,support extended unit,plastic case the specification of 7415TW:No. Parameter Description 1Model No:7415TW-201R2Voltage RequirementAC 110-240V,50/60Hz3Power ConsumptionStand by <5mA, Working <50mA,4Connection methodTwo wire for audio, two wire for lock release;5CommunicationSimultaneous type6Communication DurationNot limited7Communication ...