... ,just need to affix the main part and the accessory separate on the door and the doorfame or two windows ,aligned(the distance should less ... about 5mm).When someone attemp to open the open the door or windows(the relative position btween the main part and accessory is changed ... to leave.Sphere of application:It suit for the house,company,warehouse,cabinet,drawer,all the palce doen't allow to open for ...