... show hotel grade.Product advantages:1.Five-in-one doorbell system combination (large room number, Strong power, economical) effectively solved ... taste,convenient for guset to recognize room in nighttime and waiter to know the room status,as well as clearner to ... use safety coefficient,and positive response of a global "energy" call.Technical parameters:1.Working voltage: 220V;50 ~ 60HZ;2.Installation ...