1 pc NO Recessed Door Contacts (Normally Open) This Alarm Door Window Sensor Will Give an Open Signal When The Magnet and Switch are Together

These are the door contact sensors that are in use with any and all commercial or residential card access systems as well as all security burglar alarm system. The door position switches operate with a built an internal magnetic reed switch that opens when the opposing magnet comes within ¾" of the door sensor. Hence when the door opens beyond the ¾" point the door position switch will switch from a open signal to an closed signal. When this happens the access control system or alarm system will sense the change in continuity and will know that the door or window has been opened. When the door or window shuts, the door sensor will notify your security system that the opening has been closed.