1.220V doorbell push switch 2.Install outside wall,show room number,D.N.D,Make up ... push switchThere are 2 Kinds1.Low voltage 12V doorbell switch :Match wih other system to use together,such as ... case(Bedside control panel,Master control case,Energy saving switch,and so on).Input voltage is 12V.2. ... High voltage 220V doorbell switch :Use alone,direct connect to 220V Live wire( ...